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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html>
<head>
<!-- Generated by HsColour, http://code.haskell.org/~malcolm/hscolour/ -->
<title>src/Database/HaskellDB/Query.hs</title>
<link type='text/css' rel='stylesheet' href='hscolour.css' />
</head>
<body>
<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances
<a name="line-2"></a>  , FlexibleContexts, UndecidableInstances
<a name="line-3"></a>  , TypeSynonymInstances #-}</span>
<a name="line-4"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-5"></a><span class='hs-comment'>-- |</span>
<a name="line-6"></a><span class='hs-comment'>-- Module      :  Query</span>
<a name="line-7"></a><span class='hs-comment'>-- Copyright   :  Daan Leijen (c) 1999, daan@cs.uu.nl</span>
<a name="line-8"></a><span class='hs-comment'>--                HWT Group (c) 2003, haskelldb-users@lists.sourceforge.net</span>
<a name="line-9"></a><span class='hs-comment'>-- License     :  BSD-style</span>
<a name="line-10"></a><span class='hs-comment'>-- </span>
<a name="line-11"></a><span class='hs-comment'>-- Maintainer  :  haskelldb-users@lists.sourceforge.net</span>
<a name="line-12"></a><span class='hs-comment'>-- Stability   :  experimental</span>
<a name="line-13"></a><span class='hs-comment'>-- Portability :  non portable</span>
<a name="line-14"></a><span class='hs-comment'>-- </span>
<a name="line-15"></a><span class='hs-comment'>-- Basic combinators for building type-safe queries.</span>
<a name="line-16"></a><span class='hs-comment'>-- The Query monad constructs a relational expression</span>
<a name="line-17"></a><span class='hs-comment'>-- ('PrimQuery'). </span>
<a name="line-18"></a><span class='hs-comment'>--</span>
<a name="line-19"></a><span class='hs-comment'>-- </span>
<a name="line-20"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-21"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Database</span><span class='hs-varop'>.</span><span class='hs-conid'>HaskellDB</span><span class='hs-varop'>.</span><span class='hs-conid'>Query</span> <span class='hs-layout'>(</span>
<a name="line-22"></a>	      <span class='hs-comment'>-- * Data and class declarations</span>
<a name="line-23"></a>	     <span class='hs-conid'>Rel</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>Attr</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>Table</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>Query</span><span class='hs-layout'>,</span> <span class='hs-conid'>Expr</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>OrderExpr</span>
<a name="line-24"></a>	     <span class='hs-layout'>,</span> <span class='hs-conid'>ToPrimExprs</span><span class='hs-layout'>,</span> <span class='hs-conid'>ConstantRecord</span>
<a name="line-25"></a>	     <span class='hs-layout'>,</span> <span class='hs-conid'>ShowConstant</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>ExprC</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>ProjectExpr</span><span class='hs-layout'>,</span> <span class='hs-conid'>ProjectRec</span><span class='hs-layout'>,</span> <span class='hs-conid'>InsertRec</span>
<a name="line-26"></a>	     <span class='hs-layout'>,</span> <span class='hs-conid'>ExprAggr</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>ExprDefault</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-27"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>copy</span><span class='hs-layout'>,</span> <span class='hs-varid'>copyAll</span><span class='hs-layout'>,</span> <span class='hs-conid'>RelToRec</span>
<a name="line-28"></a>	      <span class='hs-comment'>-- * Operators</span>
<a name="line-29"></a>	     <span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>.==.</span><span class='hs-layout'>)</span> <span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>.&lt;&gt;.</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>.&lt;.</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>.&lt;=.</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>.&gt;.</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>.&gt;=.</span><span class='hs-layout'>)</span>
<a name="line-30"></a>	     <span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>.&amp;&amp;.</span><span class='hs-layout'>)</span> <span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>.||.</span><span class='hs-layout'>)</span>
<a name="line-31"></a>	     <span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>.*.</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>./.</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>.+.</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>.-.</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>.%.</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>.++.</span><span class='hs-layout'>)</span>
<a name="line-32"></a>             <span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>&lt;&lt;</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>&lt;&lt;-</span><span class='hs-layout'>)</span>
<a name="line-33"></a>	      <span class='hs-comment'>-- * Function declarations</span>
<a name="line-34"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>project</span><span class='hs-layout'>,</span> <span class='hs-varid'>restrict</span><span class='hs-layout'>,</span> <span class='hs-varid'>table</span><span class='hs-layout'>,</span> <span class='hs-varid'>unique</span>
<a name="line-35"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>union</span><span class='hs-layout'>,</span> <span class='hs-varid'>intersect</span><span class='hs-layout'>,</span> <span class='hs-varid'>divide</span><span class='hs-layout'>,</span> <span class='hs-varid'>minus</span>
<a name="line-36"></a>	     <span class='hs-layout'>,</span> <span class='hs-sel'>_not</span><span class='hs-layout'>,</span> <span class='hs-varid'>like</span><span class='hs-layout'>,</span> <span class='hs-sel'>_in</span><span class='hs-layout'>,</span> <span class='hs-varid'>cat</span><span class='hs-layout'>,</span> <span class='hs-sel'>_length</span>
<a name="line-37"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>isNull</span><span class='hs-layout'>,</span> <span class='hs-varid'>notNull</span>
<a name="line-38"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>fromNull</span><span class='hs-layout'>,</span> <span class='hs-varid'>fromVal</span>
<a name="line-39"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>constant</span><span class='hs-layout'>,</span> <span class='hs-varid'>constVal</span><span class='hs-layout'>,</span> <span class='hs-varid'>constNull</span><span class='hs-layout'>,</span> <span class='hs-varid'>constExpr</span>
<a name="line-40"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>param</span><span class='hs-layout'>,</span> <span class='hs-varid'>namedParam</span><span class='hs-layout'>,</span> <span class='hs-conid'>Args</span><span class='hs-layout'>,</span> <span class='hs-varid'>func</span><span class='hs-layout'>,</span> <span class='hs-varid'>cast</span>
<a name="line-41"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>toStr</span><span class='hs-layout'>,</span> <span class='hs-varid'>coerce</span> <span class='hs-layout'>,</span> <span class='hs-varid'>select</span>
<a name="line-42"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>count</span><span class='hs-layout'>,</span> <span class='hs-sel'>_sum</span><span class='hs-layout'>,</span> <span class='hs-sel'>_max</span><span class='hs-layout'>,</span> <span class='hs-sel'>_min</span><span class='hs-layout'>,</span> <span class='hs-varid'>avg</span> <span class='hs-layout'>,</span> <span class='hs-varid'>literal</span>
<a name="line-43"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>stddev</span><span class='hs-layout'>,</span> <span class='hs-varid'>stddevP</span><span class='hs-layout'>,</span> <span class='hs-varid'>variance</span><span class='hs-layout'>,</span> <span class='hs-varid'>varianceP</span>
<a name="line-44"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>asc</span><span class='hs-layout'>,</span> <span class='hs-varid'>desc</span><span class='hs-layout'>,</span> <span class='hs-varid'>order</span> <span class='hs-layout'>,</span> <span class='hs-varid'>top</span>
<a name="line-45"></a>	     <span class='hs-layout'>,</span> <span class='hs-sel'>_case</span> <span class='hs-layout'>,</span> <span class='hs-sel'>_default</span>
<a name="line-46"></a>	     <span class='hs-comment'>-- * Internals</span>
<a name="line-47"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>runQuery</span><span class='hs-layout'>,</span> <span class='hs-varid'>runQueryRel</span><span class='hs-layout'>,</span> <span class='hs-varid'>unQuery</span>
<a name="line-48"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>subQuery</span>
<a name="line-49"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>attribute</span><span class='hs-layout'>,</span> <span class='hs-varid'>attributeName</span><span class='hs-layout'>,</span> <span class='hs-varid'>tableName</span><span class='hs-layout'>,</span> <span class='hs-varid'>baseTable</span><span class='hs-layout'>,</span> <span class='hs-varid'>emptyTable</span>
<a name="line-50"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>exprs</span><span class='hs-layout'>,</span> <span class='hs-varid'>labels</span><span class='hs-layout'>,</span> <span class='hs-varid'>tableRec</span> 
<a name="line-51"></a>	     <span class='hs-layout'>,</span> <span class='hs-varid'>constantRecord</span>
<a name="line-52"></a>	     <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-53"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Database</span><span class='hs-varop'>.</span><span class='hs-conid'>HaskellDB</span><span class='hs-varop'>.</span><span class='hs-conid'>HDBRec</span> 
<a name="line-54"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Database</span><span class='hs-varop'>.</span><span class='hs-conid'>HaskellDB</span><span class='hs-varop'>.</span><span class='hs-conid'>PrimQuery</span>
<a name="line-55"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Database</span><span class='hs-varop'>.</span><span class='hs-conid'>HaskellDB</span><span class='hs-varop'>.</span><span class='hs-conid'>BoundedString</span>
<a name="line-56"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Database</span><span class='hs-varop'>.</span><span class='hs-conid'>HaskellDB</span><span class='hs-varop'>.</span><span class='hs-conid'>BoundedList</span>
<a name="line-57"></a>
<a name="line-58"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>Time</span> <span class='hs-layout'>(</span><span class='hs-conid'>CalendarTime</span><span class='hs-layout'>)</span>
<a name="line-59"></a>
<a name="line-60"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-61"></a><span class='hs-comment'>-- Operators</span>
<a name="line-62"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-63"></a>
<a name="line-64"></a><span class='hs-keyword'>infix</span>   <span class='hs-num'>8</span> <span class='hs-varop'>`like`</span><span class='hs-layout'>,</span> <span class='hs-varop'>`_in`</span>
<a name="line-65"></a><span class='hs-keyword'>infixl</span>  <span class='hs-num'>7</span> <span class='hs-varop'>.*.</span><span class='hs-layout'>,</span> <span class='hs-varop'>./.</span><span class='hs-layout'>,</span> <span class='hs-varop'>.%.</span>
<a name="line-66"></a><span class='hs-keyword'>infixl</span>  <span class='hs-num'>6</span> <span class='hs-varop'>.+.</span><span class='hs-layout'>,</span><span class='hs-varop'>.-.</span>
<a name="line-67"></a><span class='hs-keyword'>infix</span>   <span class='hs-num'>6</span> <span class='hs-varop'>&lt;&lt;</span><span class='hs-layout'>,</span> <span class='hs-varop'>&lt;&lt;-</span>
<a name="line-68"></a><span class='hs-keyword'>infixr</span>  <span class='hs-num'>5</span> <span class='hs-varop'>.++.</span>
<a name="line-69"></a><span class='hs-keyword'>infix</span>   <span class='hs-num'>4</span> <span class='hs-varop'>.==.</span><span class='hs-layout'>,</span> <span class='hs-varop'>.&lt;&gt;.</span><span class='hs-layout'>,</span> <span class='hs-varop'>.&lt;.</span><span class='hs-layout'>,</span> <span class='hs-varop'>.&lt;=.</span><span class='hs-layout'>,</span> <span class='hs-varop'>.&gt;.</span><span class='hs-layout'>,</span> <span class='hs-varop'>.&gt;=.</span>
<a name="line-70"></a><span class='hs-keyword'>infixr</span>  <span class='hs-num'>3</span> <span class='hs-varop'>.&amp;&amp;.</span>
<a name="line-71"></a><span class='hs-keyword'>infixr</span>  <span class='hs-num'>2</span> <span class='hs-varop'>.||.</span>
<a name="line-72"></a>
<a name="line-73"></a><span class='hs-comment'>----------------------------------------------------------</span>
<a name="line-74"></a><span class='hs-comment'>-- Data definitions. </span>
<a name="line-75"></a><span class='hs-comment'>----------------------------------------------------------</span>
<a name="line-76"></a>
<a name="line-77"></a><a name="Rel"></a><span class='hs-comment'>-- | Type of relations, contains the attributes</span>
<a name="line-78"></a><a name="Rel"></a><span class='hs-comment'>--   of the relation and an 'Alias' to which the</span>
<a name="line-79"></a><a name="Rel"></a><span class='hs-comment'>--   attributes are renamed in the 'PrimQuery'.</span>
<a name="line-80"></a><a name="Rel"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span>      <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Rel</span> <span class='hs-conid'>Alias</span> <span class='hs-conid'>Scheme</span>
<a name="line-81"></a>
<a name="line-82"></a><a name="Expr"></a><span class='hs-comment'>-- | Type of normal expressions, contains the untyped PrimExpr.</span>
<a name="line-83"></a><a name="Expr"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>     <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>PrimExpr</span>
<a name="line-84"></a>		<span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span><span class='hs-conid'>Read</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>)</span>
<a name="line-85"></a>
<a name="line-86"></a><a name="ExprAggr"></a><span class='hs-comment'>-- | Type of aggregate expressions.</span>
<a name="line-87"></a><a name="ExprAggr"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-conid'>PrimExpr</span> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span><span class='hs-conid'>Read</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>)</span>
<a name="line-88"></a>
<a name="line-89"></a><a name="ExprDefault"></a><span class='hs-comment'>-- | The type of default expressions.</span>
<a name="line-90"></a><a name="ExprDefault"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>ExprDefault</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ExprDefault</span> <span class='hs-conid'>PrimExpr</span> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span><span class='hs-conid'>Read</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>)</span>
<a name="line-91"></a>
<a name="line-92"></a><a name="Table"></a><span class='hs-comment'>-- | Basic tables, contains table name and an</span>
<a name="line-93"></a><a name="Table"></a><span class='hs-comment'>--   association from attributes to attribute</span>
<a name="line-94"></a><a name="Table"></a><span class='hs-comment'>--   names in the real table.</span>
<a name="line-95"></a><a name="Table"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Table</span> <span class='hs-varid'>r</span>    <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Table</span> <span class='hs-conid'>TableName</span> <span class='hs-conid'>Assoc</span>
<a name="line-96"></a>
<a name="line-97"></a><a name="Attr"></a><span class='hs-comment'>-- | Typed attributes</span>
<a name="line-98"></a><a name="Attr"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Attr</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span>   <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Attr</span> <span class='hs-conid'>Attribute</span>
<a name="line-99"></a>
<a name="line-100"></a><a name="Alias"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>Alias</span>      <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Int</span>
<a name="line-101"></a>
<a name="line-102"></a><a name="QState"></a><span class='hs-comment'>-- | A Query monad provides unique names (aliases)</span>
<a name="line-103"></a><a name="QState"></a><span class='hs-comment'>--   and constructs a PrimQuery.</span>
<a name="line-104"></a><a name="QState"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>QState</span>     <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>Alias</span><span class='hs-layout'>,</span><span class='hs-conid'>PrimQuery</span><span class='hs-layout'>)</span>
<a name="line-105"></a>
<a name="line-106"></a><a name="Query"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Query</span> <span class='hs-varid'>a</span>    <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>QState</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span><span class='hs-conid'>QState</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-107"></a>
<a name="line-108"></a>
<a name="line-109"></a><a name="scheme"></a><span class='hs-definition'>scheme</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Scheme</span>
<a name="line-110"></a><span class='hs-definition'>scheme</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>s</span>
<a name="line-111"></a>
<a name="line-112"></a><a name="attributeName"></a><span class='hs-definition'>attributeName</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Attr</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Attribute</span>
<a name="line-113"></a><span class='hs-definition'>attributeName</span> <span class='hs-layout'>(</span><span class='hs-conid'>Attr</span> <span class='hs-varid'>name</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>name</span>
<a name="line-114"></a>
<a name="line-115"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-116"></a><span class='hs-comment'>-- Expression and record classes.</span>
<a name="line-117"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-118"></a>
<a name="line-119"></a><a name="ExprC"></a><span class='hs-comment'>-- | Class of expression types.</span>
<a name="line-120"></a><a name="ExprC"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>ExprC</span> <span class='hs-varid'>e</span> <span class='hs-keyword'>where</span>
<a name="line-121"></a>    <span class='hs-comment'>-- | Get the underlying untyped 'PrimExpr'.</span>
<a name="line-122"></a>    <span class='hs-varid'>primExpr</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>e</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>PrimExpr</span>
<a name="line-123"></a><a name="instance%20ExprC%20Expr"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ExprC</span> <span class='hs-conid'>Expr</span> <span class='hs-keyword'>where</span> <span class='hs-varid'>primExpr</span> <span class='hs-keyglyph'>~</span><span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>e</span>
<a name="line-124"></a><a name="instance%20ExprC%20ExprAggr"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ExprC</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-keyword'>where</span> <span class='hs-varid'>primExpr</span> <span class='hs-keyglyph'>~</span><span class='hs-layout'>(</span><span class='hs-conid'>ExprAggr</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>e</span>
<a name="line-125"></a><a name="instance%20ExprC%20ExprDefault"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ExprC</span> <span class='hs-conid'>ExprDefault</span> <span class='hs-keyword'>where</span> <span class='hs-varid'>primExpr</span> <span class='hs-keyglyph'>~</span><span class='hs-layout'>(</span><span class='hs-conid'>ExprDefault</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>e</span>
<a name="line-126"></a>
<a name="line-127"></a><a name="InsertExpr"></a><span class='hs-comment'>-- | Class of expressions that can be used with 'insert'.</span>
<a name="line-128"></a><a name="InsertExpr"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>ExprC</span> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>InsertExpr</span> <span class='hs-varid'>e</span>
<a name="line-129"></a><a name="instance%20InsertRec%20(RecCons%20f%20(e%20a)%20r)%20(RecCons%20f%20(Expr%20a)%20er)%20--%20%7c%20Class%20of%20expressions%20that%20can%20be%20used%20with%20'project'.%20class%20ExprC%20e%20=%3e%20ProjectExpr%20e%20instance%20ProjectExpr%20Expr%20instance%20ProjectExpr%20ExprAggr%20--%20%7c%20Class%20of%20records%20that%20can%20be%20used%20with%20'project'.%20--%20All%20all%20the%20values%20must%20be%20instances%20of%20'ProjectExpr'%20for%20the%20--%20record%20to%20be%20an%20instance%20of%20'ProjectRec'.%20class%20ProjectRec%20r%20er%20%7c%20r%20-%3e%20er%20instance%20ProjectRec%20RecNil%20RecNil%20instance%20(ProjectExpr%20e,%20ProjectRec%20r%20er)%20=%3e%20ProjectRec%20(RecCons%20f%20(e%20a)%20r)%20(RecCons%20f%20(Expr%20a)%20er)%20-----------------------------------------------------------%20--%20Record%20operators%20-----------------------------------------------------------%20--%20%7c%20Creates%20a%20record%20field.%20--%20Similar%20to%20'(.=.)',%20but%20gets%20the%20field%20label%20from%20an%20'Attr'.%20(%20%3c%3c%20)%20::%20Attr%20f%20a%20--%20%5e%20Label%20-%3e%20e%20a%20--%20%5e%20Expression%20-%3e%20Record%20(RecCons%20f%20(e%20a)%20RecNil)%20--%20%5e%20New%20record%20_%20%3c%3c%20x%20=%20RecCons%20x%20--%20%7c%20Convenience%20operator%20for%20constructing%20records%20of%20constants.%20--%20Useful%20primarily%20with%20'insert'.%20--%20@f%20%3c%3c-%20x@%20is%20the%20same%20as%20@f%20%3c%3c%20constant%20x@%20(%20%3c%3c-%20)%20::%20ShowConstant%20a%20=%3e%20Attr%20f%20a%20--%20%5e%20Field%20label%20-%3e%20a%20--%20%5e%20Field%20value%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20--%20%5e%20New%20record%20f%20%3c%3c-%20x%20=%20f%20%3c%3c%20constant%20x%20--%20%7c%20Creates%20a%20single-field%20record%20from%20an%20attribute%20and%20a%20table.%20Useful%20--%20for%20building%20projections%20that%20will%20re-use%20the%20same%20attribute%20name.%20@copy%20attr%20tbl@%20is%20--%20equivalent%20to:%20--%20--%20@attr%20.=.%20(tbl%20.!.%20attr)@%20--%20copy%20::%20(HasField%20f%20r)%20=%3e%20Attr%20f%20a%20-%3e%20Rel%20r%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20copy%20attr%20tbl%20=%20attr%20%3c%3c%20tbl%20!%20attr%20--%20%7c%20Copies%20all%20columns%20in%20the%20relation%20given.%20Useful%20for%20appending%20--%20the%20remaining%20columns%20in%20a%20table%20to%20a%20projection.%20For%20example:%20--%20--%20%3e%20query%20=%20do%20--%20%3e%20tbl%20%3c-%20table%20some_table%20--%20%3e%20project%20$%20copyAll%20tbl%20--%20--%20will%20add%20all%20columns%20in%20%22some_table%22%20to%20the%20query.%20copyAll%20::%20(RelToRec%20r)%20=%3e%20Rel%20r%20-%3e%20Record%20r%20copyAll%20=%20relToRec%20--%20%7c%20Helper%20class%20which%20gives%20a%20polymorphic%20--%20copy%20function%20that%20can%20turn%20a%20Rel%20into%20a%20Record.%20class%20RelToRec%20a"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>InsertExpr</span> <span class='hs-conid'>Expr</span>
<a name="line-130"></a><a name="instance%20InsertRec%20(RecCons%20f%20(e%20a)%20r)%20(RecCons%20f%20(Expr%20a)%20er)%20--%20%7c%20Class%20of%20expressions%20that%20can%20be%20used%20with%20'project'.%20class%20ExprC%20e%20=%3e%20ProjectExpr%20e%20instance%20ProjectExpr%20Expr%20instance%20ProjectExpr%20ExprAggr%20--%20%7c%20Class%20of%20records%20that%20can%20be%20used%20with%20'project'.%20--%20All%20all%20the%20values%20must%20be%20instances%20of%20'ProjectExpr'%20for%20the%20--%20record%20to%20be%20an%20instance%20of%20'ProjectRec'.%20class%20ProjectRec%20r%20er%20%7c%20r%20-%3e%20er%20instance%20ProjectRec%20RecNil%20RecNil%20instance%20(ProjectExpr%20e,%20ProjectRec%20r%20er)%20=%3e%20ProjectRec%20(RecCons%20f%20(e%20a)%20r)%20(RecCons%20f%20(Expr%20a)%20er)%20-----------------------------------------------------------%20--%20Record%20operators%20-----------------------------------------------------------%20--%20%7c%20Creates%20a%20record%20field.%20--%20Similar%20to%20'(.=.)',%20but%20gets%20the%20field%20label%20from%20an%20'Attr'.%20(%20%3c%3c%20)%20::%20Attr%20f%20a%20--%20%5e%20Label%20-%3e%20e%20a%20--%20%5e%20Expression%20-%3e%20Record%20(RecCons%20f%20(e%20a)%20RecNil)%20--%20%5e%20New%20record%20_%20%3c%3c%20x%20=%20RecCons%20x%20--%20%7c%20Convenience%20operator%20for%20constructing%20records%20of%20constants.%20--%20Useful%20primarily%20with%20'insert'.%20--%20@f%20%3c%3c-%20x@%20is%20the%20same%20as%20@f%20%3c%3c%20constant%20x@%20(%20%3c%3c-%20)%20::%20ShowConstant%20a%20=%3e%20Attr%20f%20a%20--%20%5e%20Field%20label%20-%3e%20a%20--%20%5e%20Field%20value%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20--%20%5e%20New%20record%20f%20%3c%3c-%20x%20=%20f%20%3c%3c%20constant%20x%20--%20%7c%20Creates%20a%20single-field%20record%20from%20an%20attribute%20and%20a%20table.%20Useful%20--%20for%20building%20projections%20that%20will%20re-use%20the%20same%20attribute%20name.%20@copy%20attr%20tbl@%20is%20--%20equivalent%20to:%20--%20--%20@attr%20.=.%20(tbl%20.!.%20attr)@%20--%20copy%20::%20(HasField%20f%20r)%20=%3e%20Attr%20f%20a%20-%3e%20Rel%20r%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20copy%20attr%20tbl%20=%20attr%20%3c%3c%20tbl%20!%20attr%20--%20%7c%20Copies%20all%20columns%20in%20the%20relation%20given.%20Useful%20for%20appending%20--%20the%20remaining%20columns%20in%20a%20table%20to%20a%20projection.%20For%20example:%20--%20--%20%3e%20query%20=%20do%20--%20%3e%20tbl%20%3c-%20table%20some_table%20--%20%3e%20project%20$%20copyAll%20tbl%20--%20--%20will%20add%20all%20columns%20in%20%22some_table%22%20to%20the%20query.%20copyAll%20::%20(RelToRec%20r)%20=%3e%20Rel%20r%20-%3e%20Record%20r%20copyAll%20=%20relToRec%20--%20%7c%20Helper%20class%20which%20gives%20a%20polymorphic%20--%20copy%20function%20that%20can%20turn%20a%20Rel%20into%20a%20Record.%20class%20RelToRec%20a"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>InsertExpr</span> <span class='hs-conid'>ExprDefault</span>
<a name="line-131"></a>
<a name="line-132"></a><a name="InsertRec"></a><span class='hs-comment'>-- | Class of records that can be used with 'insert'. </span>
<a name="line-133"></a><a name="InsertRec"></a><span class='hs-comment'>--   All all the values must be instances of 'InsertExpr' for the</span>
<a name="line-134"></a><a name="InsertRec"></a><span class='hs-comment'>--   record to be an instance of 'InsertRec'.</span>
<a name="line-135"></a><a name="InsertRec"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>InsertRec</span> <span class='hs-varid'>r</span> <span class='hs-varid'>er</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>er</span>
<a name="line-136"></a><a name="instance%20InsertRec%20(RecCons%20f%20(e%20a)%20r)%20(RecCons%20f%20(Expr%20a)%20er)%20--%20%7c%20Class%20of%20expressions%20that%20can%20be%20used%20with%20'project'.%20class%20ExprC%20e%20=%3e%20ProjectExpr%20e%20instance%20ProjectExpr%20Expr%20instance%20ProjectExpr%20ExprAggr%20--%20%7c%20Class%20of%20records%20that%20can%20be%20used%20with%20'project'.%20--%20All%20all%20the%20values%20must%20be%20instances%20of%20'ProjectExpr'%20for%20the%20--%20record%20to%20be%20an%20instance%20of%20'ProjectRec'.%20class%20ProjectRec%20r%20er%20%7c%20r%20-%3e%20er%20instance%20ProjectRec%20RecNil%20RecNil%20instance%20(ProjectExpr%20e,%20ProjectRec%20r%20er)%20=%3e%20ProjectRec%20(RecCons%20f%20(e%20a)%20r)%20(RecCons%20f%20(Expr%20a)%20er)%20-----------------------------------------------------------%20--%20Record%20operators%20-----------------------------------------------------------%20--%20%7c%20Creates%20a%20record%20field.%20--%20Similar%20to%20'(.=.)',%20but%20gets%20the%20field%20label%20from%20an%20'Attr'.%20(%20%3c%3c%20)%20::%20Attr%20f%20a%20--%20%5e%20Label%20-%3e%20e%20a%20--%20%5e%20Expression%20-%3e%20Record%20(RecCons%20f%20(e%20a)%20RecNil)%20--%20%5e%20New%20record%20_%20%3c%3c%20x%20=%20RecCons%20x%20--%20%7c%20Convenience%20operator%20for%20constructing%20records%20of%20constants.%20--%20Useful%20primarily%20with%20'insert'.%20--%20@f%20%3c%3c-%20x@%20is%20the%20same%20as%20@f%20%3c%3c%20constant%20x@%20(%20%3c%3c-%20)%20::%20ShowConstant%20a%20=%3e%20Attr%20f%20a%20--%20%5e%20Field%20label%20-%3e%20a%20--%20%5e%20Field%20value%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20--%20%5e%20New%20record%20f%20%3c%3c-%20x%20=%20f%20%3c%3c%20constant%20x%20--%20%7c%20Creates%20a%20single-field%20record%20from%20an%20attribute%20and%20a%20table.%20Useful%20--%20for%20building%20projections%20that%20will%20re-use%20the%20same%20attribute%20name.%20@copy%20attr%20tbl@%20is%20--%20equivalent%20to:%20--%20--%20@attr%20.=.%20(tbl%20.!.%20attr)@%20--%20copy%20::%20(HasField%20f%20r)%20=%3e%20Attr%20f%20a%20-%3e%20Rel%20r%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20copy%20attr%20tbl%20=%20attr%20%3c%3c%20tbl%20!%20attr%20--%20%7c%20Copies%20all%20columns%20in%20the%20relation%20given.%20Useful%20for%20appending%20--%20the%20remaining%20columns%20in%20a%20table%20to%20a%20projection.%20For%20example:%20--%20--%20%3e%20query%20=%20do%20--%20%3e%20tbl%20%3c-%20table%20some_table%20--%20%3e%20project%20$%20copyAll%20tbl%20--%20--%20will%20add%20all%20columns%20in%20%22some_table%22%20to%20the%20query.%20copyAll%20::%20(RelToRec%20r)%20=%3e%20Rel%20r%20-%3e%20Record%20r%20copyAll%20=%20relToRec%20--%20%7c%20Helper%20class%20which%20gives%20a%20polymorphic%20--%20copy%20function%20that%20can%20turn%20a%20Rel%20into%20a%20Record.%20class%20RelToRec%20a"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>InsertRec</span> <span class='hs-conid'>RecNil</span> <span class='hs-conid'>RecNil</span>
<a name="line-137"></a><a name="instance%20InsertRec%20(RecCons%20f%20(e%20a)%20r)%20(RecCons%20f%20(Expr%20a)%20er)%20--%20%7c%20Class%20of%20expressions%20that%20can%20be%20used%20with%20'project'.%20class%20ExprC%20e%20=%3e%20ProjectExpr%20e%20instance%20ProjectExpr%20Expr%20instance%20ProjectExpr%20ExprAggr%20--%20%7c%20Class%20of%20records%20that%20can%20be%20used%20with%20'project'.%20--%20All%20all%20the%20values%20must%20be%20instances%20of%20'ProjectExpr'%20for%20the%20--%20record%20to%20be%20an%20instance%20of%20'ProjectRec'.%20class%20ProjectRec%20r%20er%20%7c%20r%20-%3e%20er%20instance%20ProjectRec%20RecNil%20RecNil%20instance%20(ProjectExpr%20e,%20ProjectRec%20r%20er)%20=%3e%20ProjectRec%20(RecCons%20f%20(e%20a)%20r)%20(RecCons%20f%20(Expr%20a)%20er)%20-----------------------------------------------------------%20--%20Record%20operators%20-----------------------------------------------------------%20--%20%7c%20Creates%20a%20record%20field.%20--%20Similar%20to%20'(.=.)',%20but%20gets%20the%20field%20label%20from%20an%20'Attr'.%20(%20%3c%3c%20)%20::%20Attr%20f%20a%20--%20%5e%20Label%20-%3e%20e%20a%20--%20%5e%20Expression%20-%3e%20Record%20(RecCons%20f%20(e%20a)%20RecNil)%20--%20%5e%20New%20record%20_%20%3c%3c%20x%20=%20RecCons%20x%20--%20%7c%20Convenience%20operator%20for%20constructing%20records%20of%20constants.%20--%20Useful%20primarily%20with%20'insert'.%20--%20@f%20%3c%3c-%20x@%20is%20the%20same%20as%20@f%20%3c%3c%20constant%20x@%20(%20%3c%3c-%20)%20::%20ShowConstant%20a%20=%3e%20Attr%20f%20a%20--%20%5e%20Field%20label%20-%3e%20a%20--%20%5e%20Field%20value%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20--%20%5e%20New%20record%20f%20%3c%3c-%20x%20=%20f%20%3c%3c%20constant%20x%20--%20%7c%20Creates%20a%20single-field%20record%20from%20an%20attribute%20and%20a%20table.%20Useful%20--%20for%20building%20projections%20that%20will%20re-use%20the%20same%20attribute%20name.%20@copy%20attr%20tbl@%20is%20--%20equivalent%20to:%20--%20--%20@attr%20.=.%20(tbl%20.!.%20attr)@%20--%20copy%20::%20(HasField%20f%20r)%20=%3e%20Attr%20f%20a%20-%3e%20Rel%20r%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20copy%20attr%20tbl%20=%20attr%20%3c%3c%20tbl%20!%20attr%20--%20%7c%20Copies%20all%20columns%20in%20the%20relation%20given.%20Useful%20for%20appending%20--%20the%20remaining%20columns%20in%20a%20table%20to%20a%20projection.%20For%20example:%20--%20--%20%3e%20query%20=%20do%20--%20%3e%20tbl%20%3c-%20table%20some_table%20--%20%3e%20project%20$%20copyAll%20tbl%20--%20--%20will%20add%20all%20columns%20in%20%22some_table%22%20to%20the%20query.%20copyAll%20::%20(RelToRec%20r)%20=%3e%20Rel%20r%20-%3e%20Record%20r%20copyAll%20=%20relToRec%20--%20%7c%20Helper%20class%20which%20gives%20a%20polymorphic%20--%20copy%20function%20that%20can%20turn%20a%20Rel%20into%20a%20Record.%20class%20RelToRec%20a"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>InsertExpr</span> <span class='hs-varid'>e</span><span class='hs-layout'>,</span> <span class='hs-conid'>InsertRec</span> <span class='hs-varid'>r</span> <span class='hs-varid'>er</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> 
<a name="line-138"></a>  <span class='hs-conid'>InsertRec</span> <span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-varid'>er</span><span class='hs-layout'>)</span>
<a name="line-139"></a>
<a name="line-140"></a><a name="ProjectExpr"></a><span class='hs-comment'>-- | Class of expressions that can be used with 'project'.</span>
<a name="line-141"></a><a name="ProjectExpr"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>ExprC</span> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>ProjectExpr</span> <span class='hs-varid'>e</span>
<a name="line-142"></a><a name="instance%20ProjectRec%20(RecCons%20f%20(e%20a)%20r)%20(RecCons%20f%20(Expr%20a)%20er)%20-----------------------------------------------------------%20--%20Record%20operators%20-----------------------------------------------------------%20--%20%7c%20Creates%20a%20record%20field.%20--%20Similar%20to%20'(.=.)',%20but%20gets%20the%20field%20label%20from%20an%20'Attr'.%20(%20%3c%3c%20)%20::%20Attr%20f%20a%20--%20%5e%20Label%20-%3e%20e%20a%20--%20%5e%20Expression%20-%3e%20Record%20(RecCons%20f%20(e%20a)%20RecNil)%20--%20%5e%20New%20record%20_%20%3c%3c%20x%20=%20RecCons%20x%20--%20%7c%20Convenience%20operator%20for%20constructing%20records%20of%20constants.%20--%20Useful%20primarily%20with%20'insert'.%20--%20@f%20%3c%3c-%20x@%20is%20the%20same%20as%20@f%20%3c%3c%20constant%20x@%20(%20%3c%3c-%20)%20::%20ShowConstant%20a%20=%3e%20Attr%20f%20a%20--%20%5e%20Field%20label%20-%3e%20a%20--%20%5e%20Field%20value%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20--%20%5e%20New%20record%20f%20%3c%3c-%20x%20=%20f%20%3c%3c%20constant%20x%20--%20%7c%20Creates%20a%20single-field%20record%20from%20an%20attribute%20and%20a%20table.%20Useful%20--%20for%20building%20projections%20that%20will%20re-use%20the%20same%20attribute%20name.%20@copy%20attr%20tbl@%20is%20--%20equivalent%20to:%20--%20--%20@attr%20.=.%20(tbl%20.!.%20attr)@%20--%20copy%20::%20(HasField%20f%20r)%20=%3e%20Attr%20f%20a%20-%3e%20Rel%20r%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20copy%20attr%20tbl%20=%20attr%20%3c%3c%20tbl%20!%20attr%20--%20%7c%20Copies%20all%20columns%20in%20the%20relation%20given.%20Useful%20for%20appending%20--%20the%20remaining%20columns%20in%20a%20table%20to%20a%20projection.%20For%20example:%20--%20--%20%3e%20query%20=%20do%20--%20%3e%20tbl%20%3c-%20table%20some_table%20--%20%3e%20project%20$%20copyAll%20tbl%20--%20--%20will%20add%20all%20columns%20in%20%22some_table%22%20to%20the%20query.%20copyAll%20::%20(RelToRec%20r)%20=%3e%20Rel%20r%20-%3e%20Record%20r%20copyAll%20=%20relToRec%20--%20%7c%20Helper%20class%20which%20gives%20a%20polymorphic%20--%20copy%20function%20that%20can%20turn%20a%20Rel%20into%20a%20Record.%20class%20RelToRec%20a"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ProjectExpr</span> <span class='hs-conid'>Expr</span>
<a name="line-143"></a><a name="instance%20ProjectRec%20(RecCons%20f%20(e%20a)%20r)%20(RecCons%20f%20(Expr%20a)%20er)%20-----------------------------------------------------------%20--%20Record%20operators%20-----------------------------------------------------------%20--%20%7c%20Creates%20a%20record%20field.%20--%20Similar%20to%20'(.=.)',%20but%20gets%20the%20field%20label%20from%20an%20'Attr'.%20(%20%3c%3c%20)%20::%20Attr%20f%20a%20--%20%5e%20Label%20-%3e%20e%20a%20--%20%5e%20Expression%20-%3e%20Record%20(RecCons%20f%20(e%20a)%20RecNil)%20--%20%5e%20New%20record%20_%20%3c%3c%20x%20=%20RecCons%20x%20--%20%7c%20Convenience%20operator%20for%20constructing%20records%20of%20constants.%20--%20Useful%20primarily%20with%20'insert'.%20--%20@f%20%3c%3c-%20x@%20is%20the%20same%20as%20@f%20%3c%3c%20constant%20x@%20(%20%3c%3c-%20)%20::%20ShowConstant%20a%20=%3e%20Attr%20f%20a%20--%20%5e%20Field%20label%20-%3e%20a%20--%20%5e%20Field%20value%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20--%20%5e%20New%20record%20f%20%3c%3c-%20x%20=%20f%20%3c%3c%20constant%20x%20--%20%7c%20Creates%20a%20single-field%20record%20from%20an%20attribute%20and%20a%20table.%20Useful%20--%20for%20building%20projections%20that%20will%20re-use%20the%20same%20attribute%20name.%20@copy%20attr%20tbl@%20is%20--%20equivalent%20to:%20--%20--%20@attr%20.=.%20(tbl%20.!.%20attr)@%20--%20copy%20::%20(HasField%20f%20r)%20=%3e%20Attr%20f%20a%20-%3e%20Rel%20r%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20copy%20attr%20tbl%20=%20attr%20%3c%3c%20tbl%20!%20attr%20--%20%7c%20Copies%20all%20columns%20in%20the%20relation%20given.%20Useful%20for%20appending%20--%20the%20remaining%20columns%20in%20a%20table%20to%20a%20projection.%20For%20example:%20--%20--%20%3e%20query%20=%20do%20--%20%3e%20tbl%20%3c-%20table%20some_table%20--%20%3e%20project%20$%20copyAll%20tbl%20--%20--%20will%20add%20all%20columns%20in%20%22some_table%22%20to%20the%20query.%20copyAll%20::%20(RelToRec%20r)%20=%3e%20Rel%20r%20-%3e%20Record%20r%20copyAll%20=%20relToRec%20--%20%7c%20Helper%20class%20which%20gives%20a%20polymorphic%20--%20copy%20function%20that%20can%20turn%20a%20Rel%20into%20a%20Record.%20class%20RelToRec%20a"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ProjectExpr</span> <span class='hs-conid'>ExprAggr</span>
<a name="line-144"></a>
<a name="line-145"></a><a name="ProjectRec"></a><span class='hs-comment'>-- | Class of records that can be used with 'project'. </span>
<a name="line-146"></a><a name="ProjectRec"></a><span class='hs-comment'>--   All all the values must be instances of 'ProjectExpr' for the</span>
<a name="line-147"></a><a name="ProjectRec"></a><span class='hs-comment'>--   record to be an instance of 'ProjectRec'.</span>
<a name="line-148"></a><a name="ProjectRec"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>ProjectRec</span> <span class='hs-varid'>r</span> <span class='hs-varid'>er</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>er</span>
<a name="line-149"></a><a name="instance%20ProjectRec%20(RecCons%20f%20(e%20a)%20r)%20(RecCons%20f%20(Expr%20a)%20er)%20-----------------------------------------------------------%20--%20Record%20operators%20-----------------------------------------------------------%20--%20%7c%20Creates%20a%20record%20field.%20--%20Similar%20to%20'(.=.)',%20but%20gets%20the%20field%20label%20from%20an%20'Attr'.%20(%20%3c%3c%20)%20::%20Attr%20f%20a%20--%20%5e%20Label%20-%3e%20e%20a%20--%20%5e%20Expression%20-%3e%20Record%20(RecCons%20f%20(e%20a)%20RecNil)%20--%20%5e%20New%20record%20_%20%3c%3c%20x%20=%20RecCons%20x%20--%20%7c%20Convenience%20operator%20for%20constructing%20records%20of%20constants.%20--%20Useful%20primarily%20with%20'insert'.%20--%20@f%20%3c%3c-%20x@%20is%20the%20same%20as%20@f%20%3c%3c%20constant%20x@%20(%20%3c%3c-%20)%20::%20ShowConstant%20a%20=%3e%20Attr%20f%20a%20--%20%5e%20Field%20label%20-%3e%20a%20--%20%5e%20Field%20value%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20--%20%5e%20New%20record%20f%20%3c%3c-%20x%20=%20f%20%3c%3c%20constant%20x%20--%20%7c%20Creates%20a%20single-field%20record%20from%20an%20attribute%20and%20a%20table.%20Useful%20--%20for%20building%20projections%20that%20will%20re-use%20the%20same%20attribute%20name.%20@copy%20attr%20tbl@%20is%20--%20equivalent%20to:%20--%20--%20@attr%20.=.%20(tbl%20.!.%20attr)@%20--%20copy%20::%20(HasField%20f%20r)%20=%3e%20Attr%20f%20a%20-%3e%20Rel%20r%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20copy%20attr%20tbl%20=%20attr%20%3c%3c%20tbl%20!%20attr%20--%20%7c%20Copies%20all%20columns%20in%20the%20relation%20given.%20Useful%20for%20appending%20--%20the%20remaining%20columns%20in%20a%20table%20to%20a%20projection.%20For%20example:%20--%20--%20%3e%20query%20=%20do%20--%20%3e%20tbl%20%3c-%20table%20some_table%20--%20%3e%20project%20$%20copyAll%20tbl%20--%20--%20will%20add%20all%20columns%20in%20%22some_table%22%20to%20the%20query.%20copyAll%20::%20(RelToRec%20r)%20=%3e%20Rel%20r%20-%3e%20Record%20r%20copyAll%20=%20relToRec%20--%20%7c%20Helper%20class%20which%20gives%20a%20polymorphic%20--%20copy%20function%20that%20can%20turn%20a%20Rel%20into%20a%20Record.%20class%20RelToRec%20a"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ProjectRec</span> <span class='hs-conid'>RecNil</span> <span class='hs-conid'>RecNil</span>
<a name="line-150"></a><a name="instance%20ProjectRec%20(RecCons%20f%20(e%20a)%20r)%20(RecCons%20f%20(Expr%20a)%20er)%20-----------------------------------------------------------%20--%20Record%20operators%20-----------------------------------------------------------%20--%20%7c%20Creates%20a%20record%20field.%20--%20Similar%20to%20'(.=.)',%20but%20gets%20the%20field%20label%20from%20an%20'Attr'.%20(%20%3c%3c%20)%20::%20Attr%20f%20a%20--%20%5e%20Label%20-%3e%20e%20a%20--%20%5e%20Expression%20-%3e%20Record%20(RecCons%20f%20(e%20a)%20RecNil)%20--%20%5e%20New%20record%20_%20%3c%3c%20x%20=%20RecCons%20x%20--%20%7c%20Convenience%20operator%20for%20constructing%20records%20of%20constants.%20--%20Useful%20primarily%20with%20'insert'.%20--%20@f%20%3c%3c-%20x@%20is%20the%20same%20as%20@f%20%3c%3c%20constant%20x@%20(%20%3c%3c-%20)%20::%20ShowConstant%20a%20=%3e%20Attr%20f%20a%20--%20%5e%20Field%20label%20-%3e%20a%20--%20%5e%20Field%20value%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20--%20%5e%20New%20record%20f%20%3c%3c-%20x%20=%20f%20%3c%3c%20constant%20x%20--%20%7c%20Creates%20a%20single-field%20record%20from%20an%20attribute%20and%20a%20table.%20Useful%20--%20for%20building%20projections%20that%20will%20re-use%20the%20same%20attribute%20name.%20@copy%20attr%20tbl@%20is%20--%20equivalent%20to:%20--%20--%20@attr%20.=.%20(tbl%20.!.%20attr)@%20--%20copy%20::%20(HasField%20f%20r)%20=%3e%20Attr%20f%20a%20-%3e%20Rel%20r%20-%3e%20Record%20(RecCons%20f%20(Expr%20a)%20RecNil)%20copy%20attr%20tbl%20=%20attr%20%3c%3c%20tbl%20!%20attr%20--%20%7c%20Copies%20all%20columns%20in%20the%20relation%20given.%20Useful%20for%20appending%20--%20the%20remaining%20columns%20in%20a%20table%20to%20a%20projection.%20For%20example:%20--%20--%20%3e%20query%20=%20do%20--%20%3e%20tbl%20%3c-%20table%20some_table%20--%20%3e%20project%20$%20copyAll%20tbl%20--%20--%20will%20add%20all%20columns%20in%20%22some_table%22%20to%20the%20query.%20copyAll%20::%20(RelToRec%20r)%20=%3e%20Rel%20r%20-%3e%20Record%20r%20copyAll%20=%20relToRec%20--%20%7c%20Helper%20class%20which%20gives%20a%20polymorphic%20--%20copy%20function%20that%20can%20turn%20a%20Rel%20into%20a%20Record.%20class%20RelToRec%20a"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>ProjectExpr</span> <span class='hs-varid'>e</span><span class='hs-layout'>,</span> <span class='hs-conid'>ProjectRec</span> <span class='hs-varid'>r</span> <span class='hs-varid'>er</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> 
<a name="line-151"></a>  <span class='hs-conid'>ProjectRec</span> <span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-varid'>er</span><span class='hs-layout'>)</span>
<a name="line-152"></a>
<a name="line-153"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-154"></a><span class='hs-comment'>-- Record operators</span>
<a name="line-155"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-156"></a>
<a name="line-157"></a><span class='hs-comment'>-- | Creates a record field.</span>
<a name="line-158"></a><span class='hs-comment'>--   Similar to '(.=.)', but gets the field label from an 'Attr'.</span>
<a name="line-159"></a><span class='hs-layout'>(</span> <span class='hs-varop'>&lt;&lt;</span> <span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Attr</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span>        <span class='hs-comment'>-- ^ Label</span>
<a name="line-160"></a>       <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>e</span> <span class='hs-varid'>a</span>                        <span class='hs-comment'>-- ^ Expression</span>
<a name="line-161"></a>       <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Record</span> <span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-conid'>RecNil</span><span class='hs-layout'>)</span>  <span class='hs-comment'>-- ^ New record</span>
<a name="line-162"></a><span class='hs-keyword'>_</span> <span class='hs-varop'>&lt;&lt;</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>RecCons</span> <span class='hs-varid'>x</span>
<a name="line-163"></a>
<a name="line-164"></a><span class='hs-comment'>-- | Convenience operator for constructing records of constants.</span>
<a name="line-165"></a><span class='hs-comment'>--   Useful primarily with 'insert'.</span>
<a name="line-166"></a><span class='hs-comment'>--   @f &lt;&lt;- x@ is the same as @f &lt;&lt; constant x@</span>
<a name="line-167"></a><span class='hs-layout'>(</span> <span class='hs-varop'>&lt;&lt;-</span> <span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ShowConstant</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span>
<a name="line-168"></a>         <span class='hs-conid'>Attr</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span>        <span class='hs-comment'>-- ^ Field label</span>
<a name="line-169"></a>      <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>a</span>                        <span class='hs-comment'>-- ^ Field value</span>
<a name="line-170"></a>      <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Record</span> <span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-conid'>RecNil</span><span class='hs-layout'>)</span>  <span class='hs-comment'>-- ^ New record</span>
<a name="line-171"></a><a name="%3c%3c-"></a><span class='hs-definition'>f</span> <span class='hs-varop'>&lt;&lt;-</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varop'>&lt;&lt;</span> <span class='hs-varid'>constant</span> <span class='hs-varid'>x</span>
<a name="line-172"></a>
<a name="line-173"></a><a name="copy"></a><span class='hs-comment'>-- | Creates a single-field record from an attribute and a table. Useful</span>
<a name="line-174"></a><span class='hs-comment'>-- for building projections that will re-use the same attribute name. @copy attr tbl@ is</span>
<a name="line-175"></a><span class='hs-comment'>-- equivalent to:</span>
<a name="line-176"></a><span class='hs-comment'>--</span>
<a name="line-177"></a><span class='hs-comment'>--   @attr .=. (tbl .!. attr)@</span>
<a name="line-178"></a><span class='hs-comment'>--</span>
<a name="line-179"></a><span class='hs-definition'>copy</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>HasField</span> <span class='hs-varid'>f</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Attr</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Record</span> <span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-conid'>RecNil</span><span class='hs-layout'>)</span>
<a name="line-180"></a><span class='hs-definition'>copy</span> <span class='hs-varid'>attr</span> <span class='hs-varid'>tbl</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>attr</span> <span class='hs-varop'>&lt;&lt;</span> <span class='hs-varid'>tbl</span> <span class='hs-varop'>!</span> <span class='hs-varid'>attr</span>
<a name="line-181"></a>
<a name="line-182"></a><a name="copyAll"></a><span class='hs-comment'>-- | Copies all columns in the relation given. Useful for appending</span>
<a name="line-183"></a><span class='hs-comment'>-- the remaining columns in a table to a projection. For example:</span>
<a name="line-184"></a><span class='hs-comment'>--</span>
<a name="line-185"></a><span class='hs-comment'>-- &gt;   query = do</span>
<a name="line-186"></a><span class='hs-comment'>-- &gt;     tbl &lt;- table some_table</span>
<a name="line-187"></a><span class='hs-comment'>-- &gt;     project $ copyAll tbl</span>
<a name="line-188"></a><span class='hs-comment'>--</span>
<a name="line-189"></a><span class='hs-comment'>-- will add all columns in "some_table" to the query.</span>
<a name="line-190"></a><span class='hs-definition'>copyAll</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>RelToRec</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Record</span> <span class='hs-varid'>r</span>
<a name="line-191"></a><span class='hs-definition'>copyAll</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>relToRec</span>
<a name="line-192"></a>
<a name="line-193"></a><a name="RelToRec"></a><span class='hs-comment'>-- | Helper class which gives a polymorphic</span>
<a name="line-194"></a><a name="RelToRec"></a><span class='hs-comment'>-- copy function that can turn a Rel into a Record.</span>
<a name="line-195"></a><a name="RelToRec"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>RelToRec</span> <span class='hs-varid'>a</span> <span class='hs-keyword'>where</span>
<a name="line-196"></a>  <span class='hs-varid'>relToRec</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Rel</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Record</span> <span class='hs-varid'>a</span>
<a name="line-197"></a>
<a name="line-198"></a><a name="instance%20RelToRec%20RecNil"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>RelToRec</span> <span class='hs-conid'>RecNil</span> <span class='hs-keyword'>where</span>
<a name="line-199"></a>  <span class='hs-varid'>relToRec</span> <span class='hs-varid'>v</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>\</span><span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>unRel</span> <span class='hs-varid'>v</span>
<a name="line-200"></a>    <span class='hs-keyword'>where</span> 
<a name="line-201"></a>      <span class='hs-varid'>unRel</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>r</span>
<a name="line-202"></a>      <span class='hs-varid'>unRel</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>error</span> <span class='hs-str'>"unRel RelToRec RecNil"</span>
<a name="line-203"></a>
<a name="line-204"></a><a name="instance%20RelToRec%20(RecCons%20f%20(Expr%20a)%20rest)"></a><span class='hs-comment'>-- All this type magic takes the first field off the Rel (Record ...) type, </span>
<a name="line-205"></a><a name="instance%20RelToRec%20(RecCons%20f%20(Expr%20a)%20rest)"></a><span class='hs-comment'>-- turns it into a (Record ...) type, and prepends it to the rest of the </span>
<a name="line-206"></a><a name="instance%20RelToRec%20(RecCons%20f%20(Expr%20a)%20rest)"></a><span class='hs-comment'>-- converted record. </span>
<a name="line-207"></a><a name="instance%20RelToRec%20(RecCons%20f%20(Expr%20a)%20rest)"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>RelToRec</span> <span class='hs-varid'>rest</span><span class='hs-layout'>,</span> <span class='hs-conid'>FieldTag</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>RelToRec</span> <span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-varid'>rest</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-208"></a>  <span class='hs-varid'>relToRec</span> <span class='hs-varid'>t</span><span class='hs-keyglyph'>@</span><span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>v</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>copy</span> <span class='hs-layout'>(</span><span class='hs-varid'>attr</span> <span class='hs-varop'>.</span> <span class='hs-varid'>fieldT</span> <span class='hs-varop'>$</span> <span class='hs-varid'>t</span><span class='hs-layout'>)</span> <span class='hs-varid'>t</span> <span class='hs-cpp'>#</span> <span class='hs-varid'>relToRec</span> <span class='hs-layout'>(</span><span class='hs-varid'>restT</span> <span class='hs-varid'>t</span><span class='hs-layout'>)</span> 
<a name="line-209"></a>    <span class='hs-keyword'>where</span>
<a name="line-210"></a>      <span class='hs-varid'>attr</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>FieldTag</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Attr</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span>
<a name="line-211"></a>      <span class='hs-varid'>attr</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Attr</span> <span class='hs-varop'>.</span> <span class='hs-varid'>fieldName</span>
<a name="line-212"></a>      <span class='hs-varid'>fieldT</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Rel</span> <span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span> <span class='hs-varid'>rest</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>f</span> 
<a name="line-213"></a>      <span class='hs-varid'>fieldT</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>error</span> <span class='hs-str'>"fieldT"</span>
<a name="line-214"></a>      <span class='hs-varid'>restT</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Rel</span> <span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span> <span class='hs-varid'>rest</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Rel</span> <span class='hs-varid'>rest</span>
<a name="line-215"></a>      <span class='hs-varid'>restT</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Rel</span> <span class='hs-varid'>v</span> <span class='hs-varid'>s</span>
<a name="line-216"></a>
<a name="line-217"></a><a name="instance%20Select%20(Attr%20f%20a)%20(Rel%20r)%20(Expr%20a)"></a><span class='hs-comment'>-- | Field selection operator. It is overloaded to work for both</span>
<a name="line-218"></a><a name="instance%20Select%20(Attr%20f%20a)%20(Rel%20r)%20(Expr%20a)"></a><span class='hs-comment'>--   relations in a query and the result of a query.</span>
<a name="line-219"></a><a name="instance%20Select%20(Attr%20f%20a)%20(Rel%20r)%20(Expr%20a)"></a><span class='hs-comment'>--   That is, it corresponds to both '!' and '!.' from the original</span>
<a name="line-220"></a><a name="instance%20Select%20(Attr%20f%20a)%20(Rel%20r)%20(Expr%20a)"></a><span class='hs-comment'>--   HaskellDB. An overloaded operator was selected because users</span>
<a name="line-221"></a><a name="instance%20Select%20(Attr%20f%20a)%20(Rel%20r)%20(Expr%20a)"></a><span class='hs-comment'>--   (and the developers) always forgot to use !. instead of !</span>
<a name="line-222"></a><a name="instance%20Select%20(Attr%20f%20a)%20(Rel%20r)%20(Expr%20a)"></a><span class='hs-comment'>--   on query results.</span>
<a name="line-223"></a><a name="instance%20Select%20(Attr%20f%20a)%20(Rel%20r)%20(Expr%20a)"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>HasField</span> <span class='hs-varid'>f</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Select</span> <span class='hs-layout'>(</span><span class='hs-conid'>Attr</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-224"></a>    <span class='hs-layout'>(</span><span class='hs-varop'>!</span><span class='hs-layout'>)</span> <span class='hs-varid'>rel</span> <span class='hs-varid'>attr</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>select</span> <span class='hs-varid'>attr</span> <span class='hs-varid'>rel</span>
<a name="line-225"></a>
<a name="line-226"></a><a name="select"></a><span class='hs-definition'>select</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>HasField</span> <span class='hs-varid'>f</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Attr</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>
<a name="line-227"></a><span class='hs-definition'>select</span> <span class='hs-layout'>(</span><span class='hs-conid'>Attr</span> <span class='hs-varid'>attribute</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>alias</span> <span class='hs-varid'>scheme</span><span class='hs-layout'>)</span>
<a name="line-228"></a>        <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>AttrExpr</span> <span class='hs-layout'>(</span><span class='hs-varid'>fresh</span> <span class='hs-varid'>alias</span> <span class='hs-varid'>attribute</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-229"></a>
<a name="line-230"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-231"></a><span class='hs-comment'>-- Basic relational operators</span>
<a name="line-232"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-233"></a>
<a name="line-234"></a><a name="project"></a><span class='hs-comment'>-- | Specifies a subset of the columns in the table.</span>
<a name="line-235"></a><span class='hs-definition'>project</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>ShowLabels</span> <span class='hs-varid'>r</span><span class='hs-layout'>,</span> <span class='hs-conid'>ToPrimExprs</span> <span class='hs-varid'>r</span><span class='hs-layout'>,</span> <span class='hs-conid'>ProjectRec</span> <span class='hs-varid'>r</span> <span class='hs-varid'>er</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Record</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>er</span><span class='hs-layout'>)</span>
<a name="line-236"></a><span class='hs-definition'>project</span> <span class='hs-varid'>r</span>
<a name="line-237"></a>        <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-238"></a>	  <span class='hs-varid'>alias</span> <span class='hs-keyglyph'>&lt;-</span> <span class='hs-varid'>newAlias</span>
<a name="line-239"></a>          <span class='hs-keyword'>let</span> <span class='hs-varid'>scheme</span>        <span class='hs-keyglyph'>=</span> <span class='hs-varid'>labels</span> <span class='hs-varid'>r</span>
<a name="line-240"></a>	      <span class='hs-varid'>assoc</span>         <span class='hs-keyglyph'>=</span> <span class='hs-varid'>zip</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-layout'>(</span><span class='hs-varid'>fresh</span> <span class='hs-varid'>alias</span><span class='hs-layout'>)</span> <span class='hs-varid'>scheme</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>exprs</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-241"></a>	  <span class='hs-varid'>updatePrimQuery</span> <span class='hs-layout'>(</span><span class='hs-varid'>extend</span> <span class='hs-varid'>assoc</span><span class='hs-layout'>)</span>
<a name="line-242"></a>          <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>alias</span> <span class='hs-varid'>scheme</span><span class='hs-layout'>)</span>
<a name="line-243"></a>
<a name="line-244"></a><a name="restrict"></a><span class='hs-comment'>-- | Restricts the records to only those who evaluates the </span>
<a name="line-245"></a><span class='hs-comment'>-- expression to True.</span>
<a name="line-246"></a><span class='hs-definition'>restrict</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-conid'>()</span>
<a name="line-247"></a><span class='hs-definition'>restrict</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>primExpr</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>updatePrimQuery_</span> <span class='hs-layout'>(</span><span class='hs-conid'>Restrict</span> <span class='hs-varid'>primExpr</span><span class='hs-layout'>)</span>
<a name="line-248"></a>
<a name="line-249"></a><a name="unique"></a><span class='hs-comment'>-- | Restricts the relation given to only return unique records. Upshot</span>
<a name="line-250"></a><span class='hs-comment'>-- is all projected attributes will be 'grouped'.</span>
<a name="line-251"></a><span class='hs-definition'>unique</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Query</span> <span class='hs-conid'>()</span>
<a name="line-252"></a><span class='hs-definition'>unique</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-varid'>i</span><span class='hs-layout'>,</span> <span class='hs-varid'>primQ</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span>
<a name="line-253"></a>    <span class='hs-comment'>-- Add all non-aggregate expressions in the query</span>
<a name="line-254"></a>    <span class='hs-comment'>-- to a groupby association list. This list holds the name</span>
<a name="line-255"></a>    <span class='hs-comment'>-- of the expression and the expression itself. Those expressions</span>
<a name="line-256"></a>    <span class='hs-comment'>-- will later by added to the groupby list in the SqlSelect built.</span>
<a name="line-257"></a>    <span class='hs-keyword'>case</span> <span class='hs-varid'>nonAggr</span> <span class='hs-varid'>primQ</span> <span class='hs-keyword'>of</span>
<a name="line-258"></a>      <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-layout'>(</span><span class='hs-conid'>()</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varid'>i</span> <span class='hs-varop'>+</span> <span class='hs-num'>1</span><span class='hs-layout'>,</span> <span class='hs-varid'>primQ</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- No non-aggregate expressions - no-op.</span>
<a name="line-259"></a>      <span class='hs-varid'>newCols</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-layout'>(</span><span class='hs-conid'>()</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varid'>i</span> <span class='hs-varop'>+</span> <span class='hs-num'>1</span><span class='hs-layout'>,</span> <span class='hs-conid'>Group</span> <span class='hs-varid'>newCols</span> <span class='hs-varid'>primQ</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-260"></a>  <span class='hs-keyword'>where</span>
<a name="line-261"></a>    <span class='hs-comment'>-- Find all non-aggregate expressions and convert</span>
<a name="line-262"></a>    <span class='hs-comment'>-- them to attribute expressions for use in group by.</span>
<a name="line-263"></a>    <span class='hs-varid'>nonAggr</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>PrimQuery</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Assoc</span>
<a name="line-264"></a>    <span class='hs-varid'>nonAggr</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>map</span> <span class='hs-varid'>toAttrExpr</span> <span class='hs-varop'>.</span> <span class='hs-varid'>filter</span> <span class='hs-layout'>(</span><span class='hs-varid'>not</span> <span class='hs-varop'>.</span> <span class='hs-varid'>isAggregate</span> <span class='hs-varop'>.</span> <span class='hs-varid'>snd</span><span class='hs-layout'>)</span> <span class='hs-varop'>.</span> <span class='hs-varid'>projected</span> <span class='hs-varop'>$</span> <span class='hs-varid'>p</span> 
<a name="line-265"></a>    <span class='hs-varid'>toAttrExpr</span> <span class='hs-layout'>(</span><span class='hs-varid'>col</span><span class='hs-layout'>,</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>col</span><span class='hs-layout'>,</span> <span class='hs-conid'>AttrExpr</span> <span class='hs-varid'>col</span><span class='hs-layout'>)</span>
<a name="line-266"></a>    <span class='hs-comment'>-- Find all projected columns from subqueries.</span>
<a name="line-267"></a>    <span class='hs-varid'>projected</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>PrimQuery</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Assoc</span>
<a name="line-268"></a>    <span class='hs-varid'>projected</span> <span class='hs-layout'>(</span><span class='hs-conid'>Project</span> <span class='hs-varid'>cols</span> <span class='hs-varid'>q</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>cols</span>
<a name="line-269"></a>    <span class='hs-varid'>projected</span> <span class='hs-layout'>(</span><span class='hs-conid'>Restrict</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>q</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>projected</span> <span class='hs-varid'>q</span>
<a name="line-270"></a>    <span class='hs-varid'>projected</span> <span class='hs-layout'>(</span><span class='hs-conid'>Binary</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>q1</span> <span class='hs-varid'>q2</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>projected</span> <span class='hs-varid'>q1</span> <span class='hs-varop'>++</span> <span class='hs-varid'>projected</span> <span class='hs-varid'>q2</span>
<a name="line-271"></a>    <span class='hs-varid'>projected</span> <span class='hs-layout'>(</span><span class='hs-conid'>BaseTable</span> <span class='hs-varid'>tblName</span> <span class='hs-varid'>cols</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>zip</span> <span class='hs-varid'>cols</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-conid'>AttrExpr</span> <span class='hs-varid'>cols</span><span class='hs-layout'>)</span>
<a name="line-272"></a>    <span class='hs-varid'>projected</span> <span class='hs-layout'>(</span><span class='hs-conid'>Special</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>q</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>projected</span> <span class='hs-varid'>q</span>
<a name="line-273"></a>    <span class='hs-comment'>-- Group and Empty are no-ops</span>
<a name="line-274"></a>    <span class='hs-varid'>projected</span> <span class='hs-layout'>(</span><span class='hs-conid'>Group</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>[]</span>
<a name="line-275"></a>    <span class='hs-varid'>projected</span> <span class='hs-conid'>Empty</span>  <span class='hs-keyglyph'>=</span> <span class='hs-conid'>[]</span>
<a name="line-276"></a>
<a name="line-277"></a>
<a name="line-278"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-279"></a><span class='hs-comment'>-- Binary operations</span>
<a name="line-280"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-281"></a>
<a name="line-282"></a><a name="binrel"></a><span class='hs-definition'>binrel</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>RelOp</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-283"></a><span class='hs-definition'>binrel</span> <span class='hs-varid'>op</span> <span class='hs-layout'>(</span><span class='hs-conid'>Query</span> <span class='hs-varid'>q1</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Query</span> <span class='hs-varid'>q2</span><span class='hs-layout'>)</span>
<a name="line-284"></a>  <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-varid'>i</span><span class='hs-layout'>,</span><span class='hs-varid'>primQ</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span>
<a name="line-285"></a>      <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>a1</span> <span class='hs-varid'>scheme1</span><span class='hs-layout'>,</span><span class='hs-layout'>(</span><span class='hs-varid'>j</span><span class='hs-layout'>,</span><span class='hs-varid'>primQ1</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>q1</span> <span class='hs-layout'>(</span><span class='hs-varid'>i</span><span class='hs-layout'>,</span><span class='hs-varid'>primQ</span><span class='hs-layout'>)</span>
<a name="line-286"></a>          <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>a2</span> <span class='hs-varid'>scheme2</span><span class='hs-layout'>,</span><span class='hs-layout'>(</span><span class='hs-varid'>alias</span><span class='hs-layout'>,</span><span class='hs-varid'>primQ2</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>q2</span> <span class='hs-layout'>(</span><span class='hs-varid'>j</span><span class='hs-layout'>,</span><span class='hs-varid'>primQ</span><span class='hs-layout'>)</span>
<a name="line-287"></a>          
<a name="line-288"></a>          <span class='hs-varid'>scheme</span>  <span class='hs-keyglyph'>=</span> <span class='hs-varid'>scheme1</span>
<a name="line-289"></a>
<a name="line-290"></a>          <span class='hs-varid'>assoc1</span>  <span class='hs-keyglyph'>=</span> <span class='hs-varid'>zip</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-layout'>(</span><span class='hs-varid'>fresh</span> <span class='hs-varid'>alias</span><span class='hs-layout'>)</span> <span class='hs-varid'>scheme1</span><span class='hs-layout'>)</span>
<a name="line-291"></a>          		<span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-layout'>(</span><span class='hs-conid'>AttrExpr</span> <span class='hs-varop'>.</span> <span class='hs-varid'>fresh</span> <span class='hs-varid'>a1</span><span class='hs-layout'>)</span> <span class='hs-varid'>scheme1</span><span class='hs-layout'>)</span>
<a name="line-292"></a>          <span class='hs-varid'>assoc2</span>  <span class='hs-keyglyph'>=</span> <span class='hs-varid'>zip</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-layout'>(</span><span class='hs-varid'>fresh</span> <span class='hs-varid'>alias</span><span class='hs-layout'>)</span> <span class='hs-varid'>scheme2</span><span class='hs-layout'>)</span>
<a name="line-293"></a>          		<span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-layout'>(</span><span class='hs-conid'>AttrExpr</span> <span class='hs-varop'>.</span> <span class='hs-varid'>fresh</span> <span class='hs-varid'>a2</span><span class='hs-layout'>)</span> <span class='hs-varid'>scheme2</span><span class='hs-layout'>)</span>
<a name="line-294"></a>
<a name="line-295"></a>          <span class='hs-varid'>r1</span>      <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Project</span> <span class='hs-varid'>assoc1</span> <span class='hs-varid'>primQ1</span>
<a name="line-296"></a>          <span class='hs-varid'>r2</span>      <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Project</span> <span class='hs-varid'>assoc2</span> <span class='hs-varid'>primQ2</span>
<a name="line-297"></a>          <span class='hs-varid'>r</span>       <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Binary</span> <span class='hs-varid'>op</span> <span class='hs-varid'>r1</span> <span class='hs-varid'>r2</span>
<a name="line-298"></a>      <span class='hs-keyword'>in</span>
<a name="line-299"></a>          <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>alias</span> <span class='hs-varid'>scheme</span><span class='hs-layout'>,</span><span class='hs-layout'>(</span><span class='hs-varid'>alias</span> <span class='hs-varop'>+</span> <span class='hs-num'>1</span><span class='hs-layout'>,</span> <span class='hs-varid'>times</span> <span class='hs-varid'>r</span> <span class='hs-varid'>primQ</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-layout'>)</span>
<a name="line-300"></a>
<a name="line-301"></a><a name="union"></a><span class='hs-comment'>-- | Return all records which are present in at least</span>
<a name="line-302"></a><span class='hs-comment'>--   one of the relations.</span>
<a name="line-303"></a><span class='hs-definition'>union</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-304"></a><span class='hs-definition'>union</span>           <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binrel</span> <span class='hs-conid'>Union</span>
<a name="line-305"></a>
<a name="line-306"></a><a name="intersect"></a><span class='hs-comment'>-- | Return all records which are present in both relations.</span>
<a name="line-307"></a><span class='hs-definition'>intersect</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> 
<a name="line-308"></a><span class='hs-definition'>intersect</span>       <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binrel</span> <span class='hs-conid'>Intersect</span>
<a name="line-309"></a>
<a name="line-310"></a><a name="divide"></a><span class='hs-comment'>-- | Not in SQL92.</span>
<a name="line-311"></a><span class='hs-definition'>divide</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> 
<a name="line-312"></a><span class='hs-definition'>divide</span>          <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binrel</span> <span class='hs-conid'>Divide</span>
<a name="line-313"></a>
<a name="line-314"></a><a name="minus"></a><span class='hs-comment'>-- | Return all records from the first relation that are not </span>
<a name="line-315"></a><span class='hs-comment'>--   present in the second relation.</span>
<a name="line-316"></a><span class='hs-definition'>minus</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-317"></a><span class='hs-definition'>minus</span>           <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binrel</span> <span class='hs-conid'>Difference</span>
<a name="line-318"></a>
<a name="line-319"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-320"></a><span class='hs-comment'>-- Tables</span>
<a name="line-321"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-322"></a>
<a name="line-323"></a><a name="table"></a><span class='hs-comment'>-- | Return all records from a specific table.</span>
<a name="line-324"></a><span class='hs-definition'>table</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>ShowRecRow</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Table</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-325"></a><span class='hs-definition'>table</span> <span class='hs-layout'>(</span><span class='hs-conid'>Table</span> <span class='hs-varid'>name</span> <span class='hs-varid'>assoc</span><span class='hs-layout'>)</span>
<a name="line-326"></a>        <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-327"></a>	  <span class='hs-varid'>alias</span> <span class='hs-keyglyph'>&lt;-</span> <span class='hs-varid'>newAlias</span>
<a name="line-328"></a>          <span class='hs-keyword'>let</span> <span class='hs-varid'>newAssoc</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>map</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-varid'>attr</span><span class='hs-layout'>,</span><span class='hs-varid'>expr</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-layout'>(</span><span class='hs-varid'>fresh</span> <span class='hs-varid'>alias</span> <span class='hs-varid'>attr</span><span class='hs-layout'>,</span><span class='hs-varid'>expr</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-varid'>assoc</span>
<a name="line-329"></a>	      <span class='hs-varid'>scheme</span>   <span class='hs-keyglyph'>=</span> <span class='hs-varid'>map</span> <span class='hs-varid'>fst</span> <span class='hs-varid'>assoc</span>
<a name="line-330"></a>	      <span class='hs-varid'>q</span>        <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Project</span> <span class='hs-varid'>newAssoc</span> <span class='hs-layout'>(</span><span class='hs-conid'>BaseTable</span> <span class='hs-varid'>name</span> <span class='hs-varid'>scheme</span><span class='hs-layout'>)</span>
<a name="line-331"></a>	  <span class='hs-varid'>updatePrimQuery</span> <span class='hs-layout'>(</span><span class='hs-varid'>times</span> <span class='hs-varid'>q</span><span class='hs-layout'>)</span>
<a name="line-332"></a>          <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>alias</span> <span class='hs-varid'>scheme</span><span class='hs-layout'>)</span>
<a name="line-333"></a>
<a name="line-334"></a><a name="tableName"></a><span class='hs-comment'>-- | Get the name of a table.</span>
<a name="line-335"></a><span class='hs-definition'>tableName</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Table</span> <span class='hs-varid'>t</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>TableName</span>
<a name="line-336"></a><span class='hs-definition'>tableName</span> <span class='hs-layout'>(</span><span class='hs-conid'>Table</span> <span class='hs-varid'>n</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>n</span>
<a name="line-337"></a>
<a name="line-338"></a><a name="tableRec"></a><span class='hs-comment'>-- Type-level function to return the type of a table's row.</span>
<a name="line-339"></a><span class='hs-definition'>tableRec</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Table</span> <span class='hs-layout'>(</span><span class='hs-conid'>Record</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Record</span> <span class='hs-varid'>r</span>
<a name="line-340"></a><span class='hs-definition'>tableRec</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>error</span> <span class='hs-str'>"tableRec should never be evaluated."</span>
<a name="line-341"></a>
<a name="line-342"></a><a name="baseTable"></a><span class='hs-comment'>-- used in table definitions</span>
<a name="line-343"></a><span class='hs-definition'>baseTable</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>ShowLabels</span> <span class='hs-varid'>r</span><span class='hs-layout'>,</span> <span class='hs-conid'>ToPrimExprs</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>TableName</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Record</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Table</span> <span class='hs-varid'>r</span>
<a name="line-344"></a><span class='hs-definition'>baseTable</span> <span class='hs-varid'>t</span> <span class='hs-varid'>r</span>   <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Table</span> <span class='hs-varid'>t</span> <span class='hs-layout'>(</span><span class='hs-varid'>zip</span> <span class='hs-layout'>(</span><span class='hs-varid'>labels</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>exprs</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-345"></a>
<a name="line-346"></a><a name="emptyTable"></a><span class='hs-comment'>-- | For queries against fake tables, such as</span>
<a name="line-347"></a><span class='hs-comment'>-- 'information_schema.information_schema_catalog_name'. Useful for</span>
<a name="line-348"></a><span class='hs-comment'>-- constructing queries that contain constant data (and do not select</span>
<a name="line-349"></a><span class='hs-comment'>-- from columns) but need a table to select from.</span>
<a name="line-350"></a><span class='hs-definition'>emptyTable</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>TableName</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Table</span> <span class='hs-layout'>(</span><span class='hs-conid'>Record</span> <span class='hs-conid'>RecNil</span><span class='hs-layout'>)</span>
<a name="line-351"></a><span class='hs-definition'>emptyTable</span> <span class='hs-varid'>t</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Table</span> <span class='hs-varid'>t</span> <span class='hs-conid'>[]</span>
<a name="line-352"></a>
<a name="line-353"></a><a name="attribute"></a><span class='hs-definition'>attribute</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>
<a name="line-354"></a><span class='hs-definition'>attribute</span> <span class='hs-varid'>name</span>  <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>AttrExpr</span> <span class='hs-varid'>name</span><span class='hs-layout'>)</span>
<a name="line-355"></a>
<a name="line-356"></a><a name="namedParam"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-357"></a><span class='hs-comment'>-- Expressions</span>
<a name="line-358"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-359"></a><span class='hs-comment'>-- | Create a named parameter with a default value.</span>
<a name="line-360"></a><span class='hs-definition'>namedParam</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Name</span> <span class='hs-comment'>-- ^ Name of the parameter.</span>
<a name="line-361"></a>  <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- ^ Default value for the parameter.</span>
<a name="line-362"></a>  <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> 
<a name="line-363"></a><span class='hs-definition'>namedParam</span> <span class='hs-varid'>n</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>def</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>ParamExpr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Just</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span> <span class='hs-varid'>def</span><span class='hs-layout'>)</span> 
<a name="line-364"></a>
<a name="line-365"></a><a name="param"></a><span class='hs-comment'>-- | Create an anonymous parameter with a default value.</span>
<a name="line-366"></a><span class='hs-definition'>param</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- ^ Default value.</span>
<a name="line-367"></a>  <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>
<a name="line-368"></a><span class='hs-definition'>param</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>def</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>ParamExpr</span> <span class='hs-conid'>Nothing</span> <span class='hs-varid'>def</span><span class='hs-layout'>)</span> 
<a name="line-369"></a>
<a name="line-370"></a><a name="unop"></a><span class='hs-definition'>unop</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>UnOp</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>b</span>
<a name="line-371"></a><span class='hs-definition'>unop</span> <span class='hs-varid'>op</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>primExpr</span><span class='hs-layout'>)</span>
<a name="line-372"></a>                <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>UnExpr</span> <span class='hs-varid'>op</span> <span class='hs-varid'>primExpr</span><span class='hs-layout'>)</span>
<a name="line-373"></a>
<a name="line-374"></a><a name="binop"></a><span class='hs-definition'>binop</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>BinOp</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>  <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>c</span>
<a name="line-375"></a><span class='hs-definition'>binop</span> <span class='hs-varid'>op</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>primExpr1</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>primExpr2</span><span class='hs-layout'>)</span>
<a name="line-376"></a>                <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>BinExpr</span> <span class='hs-varid'>op</span> <span class='hs-varid'>primExpr1</span> <span class='hs-varid'>primExpr2</span><span class='hs-layout'>)</span>
<a name="line-377"></a>
<a name="line-378"></a><a name=".==."></a><span class='hs-comment'>-- | Equality comparison on Exprs, = in SQL.</span>
<a name="line-379"></a><span class='hs-layout'>(</span><span class='hs-varop'>.==.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Eq</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span>
<a name="line-380"></a><span class='hs-layout'>(</span><span class='hs-varop'>.==.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binop</span> <span class='hs-conid'>OpEq</span>
<a name="line-381"></a>
<a name="line-382"></a><a name=".%3c%3e."></a><span class='hs-comment'>-- | Inequality on Exprs, &lt;&gt; in SQL.</span>
<a name="line-383"></a><span class='hs-layout'>(</span><span class='hs-varop'>.&lt;&gt;.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Eq</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span>
<a name="line-384"></a><span class='hs-layout'>(</span><span class='hs-varop'>.&lt;&gt;.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binop</span> <span class='hs-conid'>OpNotEq</span>
<a name="line-385"></a>
<a name="line-386"></a><a name=".%3c."></a><span class='hs-layout'>(</span><span class='hs-varop'>.&lt;.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Ord</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span>
<a name="line-387"></a><span class='hs-layout'>(</span><span class='hs-varop'>.&lt;.</span><span class='hs-layout'>)</span>  <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binop</span> <span class='hs-conid'>OpLt</span>
<a name="line-388"></a>
<a name="line-389"></a><a name=".%3c=."></a><span class='hs-layout'>(</span><span class='hs-varop'>.&lt;=.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Ord</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span>
<a name="line-390"></a><span class='hs-layout'>(</span><span class='hs-varop'>.&lt;=.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binop</span> <span class='hs-conid'>OpLtEq</span>
<a name="line-391"></a>
<a name="line-392"></a><a name=".%3e."></a><span class='hs-layout'>(</span><span class='hs-varop'>.&gt;.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Ord</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span>
<a name="line-393"></a><span class='hs-layout'>(</span><span class='hs-varop'>.&gt;.</span><span class='hs-layout'>)</span>  <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binop</span> <span class='hs-conid'>OpGt</span>
<a name="line-394"></a>
<a name="line-395"></a><a name=".%3e=."></a><span class='hs-layout'>(</span><span class='hs-varop'>.&gt;=.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Ord</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span>
<a name="line-396"></a><span class='hs-layout'>(</span><span class='hs-varop'>.&gt;=.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binop</span> <span class='hs-conid'>OpGtEq</span>
<a name="line-397"></a>
<a name="line-398"></a><span class='hs-comment'>-- | The inverse of an Expr Bool.</span>
<a name="line-399"></a><span class='hs-sel'>_not</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span>
<a name="line-400"></a><span class='hs-sel'>_not</span>   <span class='hs-keyglyph'>=</span> <span class='hs-varid'>unop</span> <span class='hs-conid'>OpNot</span>
<a name="line-401"></a>
<a name="line-402"></a><a name=".&&."></a><span class='hs-comment'>-- | \"Logical and\" on 'Expr', AND in SQL.</span>
<a name="line-403"></a><span class='hs-layout'>(</span><span class='hs-varop'>.&amp;&amp;.</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span>
<a name="line-404"></a><span class='hs-layout'>(</span><span class='hs-varop'>.&amp;&amp;.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binop</span> <span class='hs-conid'>OpAnd</span>
<a name="line-405"></a>
<a name="line-406"></a><a name=".%7c%7c."></a><span class='hs-comment'>-- | \"Logical or\" on 'Expr'. OR in SQL.</span>
<a name="line-407"></a><span class='hs-layout'>(</span><span class='hs-varop'>.||.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span>
<a name="line-408"></a><span class='hs-layout'>(</span><span class='hs-varop'>.||.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binop</span> <span class='hs-conid'>OpOr</span>
<a name="line-409"></a>
<a name="line-410"></a><a name="like"></a><span class='hs-comment'>-- | The HaskellDB counterpart to the SQL LIKE keyword.</span>
<a name="line-411"></a><span class='hs-comment'>-- In the expresions, % is a wildcard representing any characters</span>
<a name="line-412"></a><span class='hs-comment'>-- in the same position relavtive to the given characters and</span>
<a name="line-413"></a><span class='hs-comment'>-- _ is a wildcard representing one character e.g.</span>
<a name="line-414"></a><span class='hs-comment'>--</span>
<a name="line-415"></a><span class='hs-comment'>-- &gt; like (constant "ABCDEFFF") (constant "AB%F_F")</span>
<a name="line-416"></a><span class='hs-comment'>-- </span>
<a name="line-417"></a><span class='hs-comment'>-- is true while</span>
<a name="line-418"></a><span class='hs-comment'>-- </span>
<a name="line-419"></a><span class='hs-comment'>-- &gt; like (constant "ABCDEF") (constant "AC%F") </span>
<a name="line-420"></a><span class='hs-comment'>-- </span>
<a name="line-421"></a><span class='hs-comment'>-- is false.</span>
<a name="line-422"></a><span class='hs-comment'>--</span>
<a name="line-423"></a><span class='hs-comment'>-- Note that SQL92 does not specify whether LIKE is case-sensitive or not.</span>
<a name="line-424"></a><span class='hs-comment'>-- Different database systems implement this differently.</span>
<a name="line-425"></a><span class='hs-definition'>like</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span>
<a name="line-426"></a><span class='hs-definition'>like</span>   <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binop</span> <span class='hs-conid'>OpLike</span>
<a name="line-427"></a>
<a name="line-428"></a><span class='hs-comment'>-- | Returns true if the value of the first operand is</span>
<a name="line-429"></a><span class='hs-comment'>--   equal to the value of any of the expressions in the </span>
<a name="line-430"></a><span class='hs-comment'>--   list operand. </span>
<a name="line-431"></a><span class='hs-sel'>_in</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Eq</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span>
<a name="line-432"></a><span class='hs-sel'>_in</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-varid'>ys</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>BinExpr</span> <span class='hs-conid'>OpIn</span> <span class='hs-varid'>x</span> <span class='hs-layout'>(</span><span class='hs-conid'>ListExpr</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>y</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>&lt;-</span> <span class='hs-varid'>ys</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-433"></a>
<a name="line-434"></a>
<a name="line-435"></a><a name="cat"></a><span class='hs-comment'>-- | Produces the concatenation of two String-expressions.</span>
<a name="line-436"></a><span class='hs-definition'>cat</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>String</span>
<a name="line-437"></a><span class='hs-definition'>cat</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binop</span> <span class='hs-conid'>OpCat</span>
<a name="line-438"></a>
<a name="line-439"></a><a name=".++."></a><span class='hs-comment'>-- | Concatenates two String-expressions. </span>
<a name="line-440"></a><span class='hs-layout'>(</span><span class='hs-varop'>.++.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>String</span>
<a name="line-441"></a><span class='hs-layout'>(</span><span class='hs-varop'>.++.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>cat</span>
<a name="line-442"></a>
<a name="line-443"></a><span class='hs-comment'>-- | Gets the length of a string.</span>
<a name="line-444"></a><span class='hs-sel'>_length</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Int</span>
<a name="line-445"></a><span class='hs-sel'>_length</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>unop</span> <span class='hs-conid'>OpLength</span>
<a name="line-446"></a>
<a name="line-447"></a><a name="numop"></a><span class='hs-definition'>numop</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Num</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>BinOp</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>
<a name="line-448"></a><span class='hs-definition'>numop</span>   <span class='hs-keyglyph'>=</span> <span class='hs-varid'>binop</span>
<a name="line-449"></a>
<a name="line-450"></a><a name=".+."></a><span class='hs-comment'>-- | Addition</span>
<a name="line-451"></a><span class='hs-layout'>(</span><span class='hs-varop'>.+.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Num</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>
<a name="line-452"></a><span class='hs-layout'>(</span><span class='hs-varop'>.+.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>numop</span> <span class='hs-conid'>OpPlus</span>
<a name="line-453"></a><a name=".-."></a><span class='hs-comment'>-- | Subtraction </span>
<a name="line-454"></a><span class='hs-layout'>(</span><span class='hs-varop'>.-.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Num</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>
<a name="line-455"></a><span class='hs-layout'>(</span><span class='hs-varop'>.-.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>numop</span> <span class='hs-conid'>OpMinus</span>
<a name="line-456"></a><a name=".*."></a><span class='hs-comment'>-- | Multiplication</span>
<a name="line-457"></a><span class='hs-layout'>(</span><span class='hs-varop'>.*.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Num</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>
<a name="line-458"></a><span class='hs-layout'>(</span><span class='hs-varop'>.*.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>numop</span> <span class='hs-conid'>OpMul</span>
<a name="line-459"></a><a name="./."></a><span class='hs-comment'>-- | Division</span>
<a name="line-460"></a><span class='hs-layout'>(</span><span class='hs-varop'>./.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Num</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>
<a name="line-461"></a><span class='hs-layout'>(</span><span class='hs-varop'>./.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>numop</span> <span class='hs-conid'>OpDiv</span>
<a name="line-462"></a><a name=".%25."></a><span class='hs-comment'>-- | Modulo</span>
<a name="line-463"></a><span class='hs-layout'>(</span><span class='hs-varop'>.%.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Num</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>
<a name="line-464"></a><span class='hs-layout'>(</span><span class='hs-varop'>.%.</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>numop</span> <span class='hs-conid'>OpMod</span>
<a name="line-465"></a>
<a name="line-466"></a><a name="isNull"></a><span class='hs-comment'>-- | Returns true if the expression is Null.</span>
<a name="line-467"></a><span class='hs-definition'>isNull</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span>
<a name="line-468"></a><span class='hs-definition'>isNull</span>  <span class='hs-keyglyph'>=</span> <span class='hs-varid'>unop</span> <span class='hs-conid'>OpIsNull</span>
<a name="line-469"></a>
<a name="line-470"></a><a name="notNull"></a><span class='hs-comment'>-- | The inverse of 'isNull', returns false</span>
<a name="line-471"></a><span class='hs-comment'>-- if the expression supplied is Null.</span>
<a name="line-472"></a><span class='hs-definition'>notNull</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span>
<a name="line-473"></a><span class='hs-definition'>notNull</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>unop</span> <span class='hs-conid'>OpIsNotNull</span>
<a name="line-474"></a>
<a name="line-475"></a><span class='hs-comment'>-- | Creates a conditional expression.</span>
<a name="line-476"></a><span class='hs-comment'>--   Returns the value of the expression corresponding to the first </span>
<a name="line-477"></a><span class='hs-comment'>--   true condition. If none of the conditions are true, the value of</span>
<a name="line-478"></a><span class='hs-comment'>--   the else-expression is returned.</span>
<a name="line-479"></a><span class='hs-sel'>_case</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-conid'>Bool</span><span class='hs-layout'>,</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span> <span class='hs-comment'>-- ^ A list of conditions and expressions.</span>
<a name="line-480"></a>      <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>                <span class='hs-comment'>-- ^ Else-expression. </span>
<a name="line-481"></a>      <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>
<a name="line-482"></a><span class='hs-sel'>_case</span> <span class='hs-varid'>cs</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>el</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>CaseExpr</span> <span class='hs-keyglyph'>[</span> <span class='hs-layout'>(</span><span class='hs-varid'>c</span><span class='hs-layout'>,</span><span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>|</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>c</span><span class='hs-layout'>,</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>&lt;-</span> <span class='hs-varid'>cs</span><span class='hs-keyglyph'>]</span> <span class='hs-varid'>el</span><span class='hs-layout'>)</span>
<a name="line-483"></a>
<a name="line-484"></a><a name="BStrToStr"></a><span class='hs-comment'>-- | Class which can convert BoundedStrings to normal strings,</span>
<a name="line-485"></a><a name="BStrToStr"></a><span class='hs-comment'>-- even inside type constructors. Useful when a field</span>
<a name="line-486"></a><a name="BStrToStr"></a><span class='hs-comment'>-- is defined as a BoundedString (e.g. "Expr BStr10" or "Expr (Maybe BStr20)") but</span>
<a name="line-487"></a><a name="BStrToStr"></a><span class='hs-comment'>-- it needs to be used in an expression context. The example below illustrates a</span>
<a name="line-488"></a><a name="BStrToStr"></a><span class='hs-comment'>-- table with at least two fields, strField and bStrField. The first is defined as</span>
<a name="line-489"></a><a name="BStrToStr"></a><span class='hs-comment'>-- containing strings, the second as containing strings up to 10 characters long. The</span>
<a name="line-490"></a><a name="BStrToStr"></a><span class='hs-comment'>-- @toStr@ function must be used to convert the bStrField into the appropriate type for</span>
<a name="line-491"></a><a name="BStrToStr"></a><span class='hs-comment'>-- projecting as the strField:</span>
<a name="line-492"></a><a name="BStrToStr"></a><span class='hs-comment'>--</span>
<a name="line-493"></a><a name="BStrToStr"></a><span class='hs-comment'>-- &gt; type SomeTable = (RecCons StrField (Expr String)</span>
<a name="line-494"></a><a name="BStrToStr"></a><span class='hs-comment'>-- &gt;                    (RecCons BStrField (Expr BStr10) ... ))</span>
<a name="line-495"></a><a name="BStrToStr"></a><span class='hs-comment'>--</span>
<a name="line-496"></a><a name="BStrToStr"></a><span class='hs-comment'>-- &gt; someTable :: Table SomeTable</span>
<a name="line-497"></a><a name="BStrToStr"></a><span class='hs-comment'>-- &gt; someTable = ...</span>
<a name="line-498"></a><a name="BStrToStr"></a><span class='hs-comment'>--</span>
<a name="line-499"></a><a name="BStrToStr"></a><span class='hs-comment'>-- &gt; strField :: Attr StrField String</span>
<a name="line-500"></a><a name="BStrToStr"></a><span class='hs-comment'>-- &gt; strField = ...</span>
<a name="line-501"></a><a name="BStrToStr"></a><span class='hs-comment'>-- &gt;</span>
<a name="line-502"></a><a name="BStrToStr"></a><span class='hs-comment'>-- &gt; bstrField :: Attr BStrField (BStr10)</span>
<a name="line-503"></a><a name="BStrToStr"></a><span class='hs-comment'>-- &gt; bstrField = ...</span>
<a name="line-504"></a><a name="BStrToStr"></a><span class='hs-comment'>-- &gt; </span>
<a name="line-505"></a><a name="BStrToStr"></a><span class='hs-comment'>-- &gt; query = do</span>
<a name="line-506"></a><a name="BStrToStr"></a><span class='hs-comment'>-- &gt;  t &lt;- table someTable</span>
<a name="line-507"></a><a name="BStrToStr"></a><span class='hs-comment'>-- &gt;  project $ strField &lt;&lt; toStr $ t ! bstrField</span>
<a name="line-508"></a><a name="BStrToStr"></a><span class='hs-comment'>--</span>
<a name="line-509"></a><a name="BStrToStr"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>BStrToStr</span> <span class='hs-varid'>s</span> <span class='hs-varid'>d</span> <span class='hs-keyword'>where</span>
<a name="line-510"></a>  <span class='hs-comment'>-- | Convert a bounded string to a real string.</span>
<a name="line-511"></a>  <span class='hs-varid'>toStr</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>d</span>
<a name="line-512"></a>
<a name="line-513"></a><a name="instance%20BStrToStr%20(Expr%20(BoundedString%20n))%20(Expr%20String)"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Size</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>BStrToStr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>BoundedString</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-514"></a>  <span class='hs-varid'>toStr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span>
<a name="line-515"></a>
<a name="line-516"></a><a name="instance%20BStrToStr%20(Expr%20(Maybe%20(BoundedString%20n)))%20(Expr%20(Maybe%20String))"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Size</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>BStrToStr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-conid'>BoundedString</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-517"></a>  <span class='hs-varid'>toStr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span>
<a name="line-518"></a>
<a name="line-519"></a><a name="instance%20BStrToStr%20(Expr%20(Maybe%20String))%20(Expr%20(Maybe%20String))"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>BStrToStr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-520"></a>  <span class='hs-varid'>toStr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span>
<a name="line-521"></a>
<a name="line-522"></a><a name="instance%20BStrToStr%20(Expr%20String)%20(Expr%20String)"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>BStrToStr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-523"></a>  <span class='hs-varid'>toStr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span>
<a name="line-524"></a>
<a name="line-525"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-526"></a><span class='hs-comment'>-- Using arbitrary SQL functions in a type-safe way.</span>
<a name="line-527"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-528"></a>
<a name="line-529"></a><a name="IsExpr"></a><span class='hs-comment'>-- | Used to implement variable length arguments to @func@, below.</span>
<a name="line-530"></a><a name="IsExpr"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>Args</span> <span class='hs-varid'>a</span> <span class='hs-keyword'>where</span>
<a name="line-531"></a>  <span class='hs-varid'>arg_</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>PrimExpr</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>a</span>
<a name="line-532"></a>
<a name="line-533"></a><a name="IsExpr"></a><span class='hs-comment'>-- | Used to limit variable argument form of @func@ to only take @Expr@ types,</span>
<a name="line-534"></a><a name="IsExpr"></a><span class='hs-comment'>-- and ignore @ExprAggr@ types.</span>
<a name="line-535"></a><a name="IsExpr"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>IsExpr</span> <span class='hs-varid'>a</span>
<a name="line-536"></a>
<a name="line-537"></a><a name="instance%20IsExpr%20(Expr%20a%20-%3e%20tail)%20instance%20IsExpr%20(Expr%20a)%20instance%20(IsExpr%20tail,%20Args%20tail)%20=%3e%20Args%20(Expr%20a%20-%3e%20tail)"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>IsExpr</span> <span class='hs-varid'>tail</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>IsExpr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>tail</span><span class='hs-layout'>)</span>
<a name="line-538"></a>
<a name="line-539"></a><a name="instance%20Args%20(Expr%20a%20-%3e%20tail)"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>IsExpr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-540"></a>
<a name="line-541"></a><a name="instance%20Args%20(Expr%20a%20-%3e%20tail)"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>IsExpr</span> <span class='hs-varid'>tail</span><span class='hs-layout'>,</span> <span class='hs-conid'>Args</span> <span class='hs-varid'>tail</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Args</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>tail</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-542"></a>  <span class='hs-varid'>arg_</span> <span class='hs-varid'>name</span> <span class='hs-varid'>exprs</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>prim</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>arg_</span> <span class='hs-varid'>name</span> <span class='hs-layout'>(</span><span class='hs-varid'>prim</span> <span class='hs-conop'>:</span> <span class='hs-varid'>exprs</span><span class='hs-layout'>)</span>
<a name="line-543"></a>
<a name="line-544"></a><a name="instance%20Args%20(Expr%20a)"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Args</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-545"></a>  <span class='hs-comment'>-- Reverse necessary because arguments are built in reverse order by instances</span>
<a name="line-546"></a>  <span class='hs-comment'>-- of Args above.</span>
<a name="line-547"></a>  <span class='hs-varid'>arg_</span> <span class='hs-varid'>name</span> <span class='hs-varid'>exprs</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>FunExpr</span> <span class='hs-varid'>name</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-varid'>exprs</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-548"></a>
<a name="line-549"></a><a name="instance%20Args%20(Expr%20a%20-%3e%20ExprAggr%20c)"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Args</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-550"></a>  <span class='hs-varid'>arg_</span> <span class='hs-varid'>name</span> <span class='hs-varid'>exprs</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>prim</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-layout'>(</span><span class='hs-conid'>AggrExpr</span> <span class='hs-layout'>(</span><span class='hs-conid'>AggrOther</span> <span class='hs-varid'>name</span><span class='hs-layout'>)</span> <span class='hs-varid'>prim</span><span class='hs-layout'>)</span>
<a name="line-551"></a>
<a name="line-552"></a><a name="func"></a><span class='hs-comment'>{- | Can be used to define SQL functions which will
<a name="line-553"></a>appear in queries. Each argument for the function is specified by its own Expr value. 
<a name="line-554"></a>Examples include:
<a name="line-555"></a>
<a name="line-556"></a>&gt;  lower :: Expr a -&gt; Expr (Maybe String) 
<a name="line-557"></a>&gt;  lower str = func "lower" str
<a name="line-558"></a>
<a name="line-559"></a>The arguments to the function do not have to be Expr if they can
<a name="line-560"></a>be converted to Expr:
<a name="line-561"></a>
<a name="line-562"></a>&gt;  data DatePart = Day | Century deriving Show 
<a name="line-563"></a>
<a name="line-564"></a>&gt;  datePart :: DatePart -&gt; Expr (Maybe CalendarTime) -&gt; Expr (Maybe Int) 
<a name="line-565"></a>&gt;  datePart date col = func "date_part" (constant $ show date) col
<a name="line-566"></a>
<a name="line-567"></a>Aggregate functions can also be defined. For example:
<a name="line-568"></a>
<a name="line-569"></a> &gt;  every :: Expr Bool -&gt; ExprAggr Bool 
<a name="line-570"></a> &gt;  every col = func "every" col
<a name="line-571"></a>
<a name="line-572"></a>Aggregates are implemented to always take one argument, so any attempt to
<a name="line-573"></a>define an aggregate with any more or less arguments will result in an error.
<a name="line-574"></a>
<a name="line-575"></a>Note that type signatures are usually required for each function defined,
<a name="line-576"></a>unless the arguments can be inferred.-}</span>
<a name="line-577"></a><span class='hs-definition'>func</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Args</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>a</span> 
<a name="line-578"></a><span class='hs-definition'>func</span> <span class='hs-varid'>name</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>arg_</span> <span class='hs-varid'>name</span> <span class='hs-conid'>[]</span> 
<a name="line-579"></a>
<a name="line-580"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-581"></a><span class='hs-comment'>-- Default values</span>
<a name="line-582"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-583"></a>
<a name="line-584"></a><span class='hs-comment'>-- | The default value of the column. Only works with 'insert'.</span>
<a name="line-585"></a><span class='hs-sel'>_default</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ExprDefault</span> <span class='hs-varid'>a</span>
<a name="line-586"></a><span class='hs-sel'>_default</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ExprDefault</span> <span class='hs-layout'>(</span><span class='hs-conid'>ConstExpr</span> <span class='hs-conid'>DefaultLit</span><span class='hs-layout'>)</span>
<a name="line-587"></a>
<a name="line-588"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-589"></a><span class='hs-comment'>-- Constants</span>
<a name="line-590"></a><span class='hs-comment'>-- Maybe we should change the set according to the </span>
<a name="line-591"></a><span class='hs-comment'>-- database backend</span>
<a name="line-592"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-593"></a>
<a name="line-594"></a><a name="ShowConstant"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>ShowConstant</span> <span class='hs-varid'>a</span> <span class='hs-keyword'>where</span>
<a name="line-595"></a>    <span class='hs-varid'>showConstant</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Literal</span>
<a name="line-596"></a>
<a name="line-597"></a><a name="instance%20ShowConstant%20String"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ShowConstant</span> <span class='hs-conid'>String</span> <span class='hs-keyword'>where</span>
<a name="line-598"></a>    <span class='hs-varid'>showConstant</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>StringLit</span>
<a name="line-599"></a><a name="instance%20ShowConstant%20Int"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ShowConstant</span> <span class='hs-conid'>Int</span> <span class='hs-keyword'>where</span>
<a name="line-600"></a>    <span class='hs-varid'>showConstant</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IntegerLit</span> <span class='hs-varop'>.</span> <span class='hs-varid'>fromIntegral</span>
<a name="line-601"></a><a name="instance%20ShowConstant%20Integer"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ShowConstant</span> <span class='hs-conid'>Integer</span> <span class='hs-keyword'>where</span>
<a name="line-602"></a>    <span class='hs-varid'>showConstant</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IntegerLit</span>
<a name="line-603"></a><a name="instance%20ShowConstant%20Double"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ShowConstant</span> <span class='hs-conid'>Double</span> <span class='hs-keyword'>where</span>
<a name="line-604"></a>    <span class='hs-varid'>showConstant</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>DoubleLit</span>
<a name="line-605"></a><a name="instance%20ShowConstant%20Bool"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ShowConstant</span> <span class='hs-conid'>Bool</span> <span class='hs-keyword'>where</span>
<a name="line-606"></a>    <span class='hs-varid'>showConstant</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>BoolLit</span>
<a name="line-607"></a>
<a name="line-608"></a><a name="instance%20ShowConstant%20CalendarTime"></a><span class='hs-comment'>-- this assumes that all databases accept both date and time even when they</span>
<a name="line-609"></a><a name="instance%20ShowConstant%20CalendarTime"></a><span class='hs-comment'>-- only want date.</span>
<a name="line-610"></a><a name="instance%20ShowConstant%20CalendarTime"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ShowConstant</span> <span class='hs-conid'>CalendarTime</span> <span class='hs-keyword'>where</span>
<a name="line-611"></a>    <span class='hs-varid'>showConstant</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>DateLit</span>
<a name="line-612"></a>
<a name="line-613"></a><a name="instance%20ShowConstant%20(Maybe%20a)"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ShowConstant</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>ShowConstant</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-614"></a>    <span class='hs-varid'>showConstant</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>maybe</span> <span class='hs-conid'>NullLit</span> <span class='hs-varid'>showConstant</span>
<a name="line-615"></a>
<a name="line-616"></a><a name="instance%20ShowConstant%20(BoundedString%20n)"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Size</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>ShowConstant</span> <span class='hs-layout'>(</span><span class='hs-conid'>BoundedString</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-617"></a>    <span class='hs-varid'>showConstant</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>showConstant</span> <span class='hs-varop'>.</span> <span class='hs-varid'>fromBounded</span>
<a name="line-618"></a>
<a name="line-619"></a><a name="constant"></a><span class='hs-comment'>-- | Creates a constant expression from a haskell value.</span>
<a name="line-620"></a><span class='hs-definition'>constant</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ShowConstant</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>
<a name="line-621"></a><span class='hs-definition'>constant</span> <span class='hs-varid'>x</span>  <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>ConstExpr</span> <span class='hs-layout'>(</span><span class='hs-varid'>showConstant</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-622"></a>
<a name="line-623"></a><a name="literal"></a><span class='hs-comment'>-- | Inserts the string literally - no escaping, no quoting.</span>
<a name="line-624"></a><span class='hs-definition'>literal</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>
<a name="line-625"></a><span class='hs-definition'>literal</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>ConstExpr</span> <span class='hs-layout'>(</span><span class='hs-conid'>OtherLit</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-626"></a>
<a name="line-627"></a><a name="fromNull"></a><span class='hs-comment'>-- | Takes a default value a and a nullable value. If the value is NULL,</span>
<a name="line-628"></a><span class='hs-comment'>--   the default value is returned, otherwise the value itself is returned.</span>
<a name="line-629"></a><span class='hs-comment'>--   Simliar to 'fromMaybe'</span>
<a name="line-630"></a><span class='hs-definition'>fromNull</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>         <span class='hs-comment'>-- ^ Default value (to be returned for 'Nothing')</span>
<a name="line-631"></a>	 <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ A nullable expression</span>
<a name="line-632"></a>	 <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>
<a name="line-633"></a><span class='hs-definition'>fromNull</span> <span class='hs-varid'>d</span> <span class='hs-varid'>x</span><span class='hs-keyglyph'>@</span><span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>px</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-sel'>_case</span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-varid'>isNull</span> <span class='hs-varid'>x</span><span class='hs-layout'>,</span> <span class='hs-varid'>d</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>px</span><span class='hs-layout'>)</span>
<a name="line-634"></a>
<a name="line-635"></a><a name="fromVal"></a><span class='hs-comment'>-- | Similar to fromNull, but takes a </span>
<a name="line-636"></a><span class='hs-comment'>-- value argument rather than an Expr.</span>
<a name="line-637"></a><span class='hs-definition'>fromVal</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ShowConstant</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-varid'>a</span> 
<a name="line-638"></a>        <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-639"></a>        <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span>
<a name="line-640"></a><span class='hs-definition'>fromVal</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fromNull</span> <span class='hs-varop'>.</span> <span class='hs-varid'>constant</span> 
<a name="line-641"></a>
<a name="line-642"></a><a name="constExpr"></a><span class='hs-comment'>-- | Turn constant data into a nullable expression. </span>
<a name="line-643"></a><span class='hs-comment'>--   Same as @constant . Just@</span>
<a name="line-644"></a><span class='hs-definition'>constExpr</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-645"></a><span class='hs-definition'>constExpr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-646"></a>
<a name="line-647"></a><a name="constVal"></a><span class='hs-comment'>-- | Turn constant data into a nullable expression. </span>
<a name="line-648"></a><span class='hs-comment'>--   Same as @constant . Just@</span>
<a name="line-649"></a><span class='hs-definition'>constVal</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ShowConstant</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-650"></a><span class='hs-definition'>constVal</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>constant</span> <span class='hs-layout'>(</span><span class='hs-conid'>Just</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-651"></a>
<a name="line-652"></a><a name="constNull"></a><span class='hs-comment'>-- | Represents a null value.</span>
<a name="line-653"></a><span class='hs-definition'>constNull</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-654"></a><span class='hs-definition'>constNull</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>ConstExpr</span> <span class='hs-conid'>NullLit</span><span class='hs-layout'>)</span>
<a name="line-655"></a>
<a name="line-656"></a><a name="cast"></a><span class='hs-comment'>-- | Generates a 'CAST' expression for the given</span>
<a name="line-657"></a><span class='hs-comment'>-- expression, using the argument given as the destination</span>
<a name="line-658"></a><span class='hs-comment'>-- type. </span>
<a name="line-659"></a><span class='hs-definition'>cast</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-comment'>-- ^ Destination type.</span>
<a name="line-660"></a>  <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- ^ Source expression.</span>
<a name="line-661"></a>  <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>b</span>
<a name="line-662"></a><span class='hs-definition'>cast</span> <span class='hs-varid'>typ</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>expr</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-layout'>(</span><span class='hs-conid'>CastExpr</span> <span class='hs-varid'>typ</span> <span class='hs-varid'>expr</span><span class='hs-layout'>)</span>
<a name="line-663"></a>
<a name="line-664"></a><a name="coerce"></a><span class='hs-comment'>-- | Coerce the type of an expression</span>
<a name="line-665"></a><span class='hs-comment'>-- to another type. Does not affect the actual</span>
<a name="line-666"></a><span class='hs-comment'>-- primitive value - only the `phantom' type.</span>
<a name="line-667"></a><span class='hs-definition'>coerce</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- ^ Source expression</span>
<a name="line-668"></a>  <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>b</span> <span class='hs-comment'>-- ^ Destination type.</span>
<a name="line-669"></a><span class='hs-definition'>coerce</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>e</span>
<a name="line-670"></a>
<a name="line-671"></a><a name="ConstantRecord"></a><span class='hs-comment'>-- | Converts records w/o Expr (usually from database</span>
<a name="line-672"></a><a name="ConstantRecord"></a><span class='hs-comment'>-- queries) to records with Expr types. </span>
<a name="line-673"></a><a name="ConstantRecord"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>ConstantRecord</span> <span class='hs-varid'>r</span> <span class='hs-varid'>cr</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>cr</span> <span class='hs-keyword'>where</span>
<a name="line-674"></a>    <span class='hs-varid'>constantRecord</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>cr</span>
<a name="line-675"></a>
<a name="line-676"></a><a name="instance%20ConstantRecord%20(Record%20r)%20(Record%20cr)"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ConstantRecord</span> <span class='hs-varid'>r</span> <span class='hs-varid'>cr</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>ConstantRecord</span> <span class='hs-layout'>(</span><span class='hs-conid'>Record</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Record</span> <span class='hs-varid'>cr</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-677"></a>    <span class='hs-varid'>constantRecord</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>n</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>constantRecord</span> <span class='hs-layout'>(</span><span class='hs-varid'>r</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span>
<a name="line-678"></a>
<a name="line-679"></a><a name="instance%20ConstantRecord%20RecNil%20RecNil"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ConstantRecord</span> <span class='hs-conid'>RecNil</span> <span class='hs-conid'>RecNil</span> <span class='hs-keyword'>where</span>
<a name="line-680"></a>    <span class='hs-varid'>constantRecord</span> <span class='hs-conid'>RecNil</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>RecNil</span>
<a name="line-681"></a>
<a name="line-682"></a><a name="instance%20ConstantRecord%20(RecCons%20f%20a%20r)%20(RecCons%20f%20(Expr%20a)%20cr)"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>ShowConstant</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>ConstantRecord</span> <span class='hs-varid'>r</span> <span class='hs-varid'>cr</span><span class='hs-layout'>)</span>
<a name="line-683"></a>    <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>ConstantRecord</span> <span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-varid'>cr</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-684"></a>    <span class='hs-varid'>constantRecord</span> <span class='hs-keyglyph'>~</span><span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>x</span> <span class='hs-varid'>rs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>RecCons</span> <span class='hs-layout'>(</span><span class='hs-varid'>constant</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>constantRecord</span> <span class='hs-varid'>rs</span><span class='hs-layout'>)</span>
<a name="line-685"></a>
<a name="line-686"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-687"></a><span class='hs-comment'>-- Aggregate operators</span>
<a name="line-688"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-689"></a>
<a name="line-690"></a><a name="aggregate"></a><span class='hs-definition'>aggregate</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>AggrOp</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-varid'>b</span>
<a name="line-691"></a><span class='hs-definition'>aggregate</span> <span class='hs-varid'>op</span> <span class='hs-layout'>(</span><span class='hs-conid'>Expr</span> <span class='hs-varid'>primExpr</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-layout'>(</span><span class='hs-conid'>AggrExpr</span> <span class='hs-varid'>op</span> <span class='hs-varid'>primExpr</span><span class='hs-layout'>)</span>
<a name="line-692"></a>
<a name="line-693"></a><a name="count"></a><span class='hs-comment'>-- | Returns the number of records (=rows) in a query.</span>
<a name="line-694"></a><span class='hs-definition'>count</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-conid'>Int</span>
<a name="line-695"></a><span class='hs-definition'>count</span> <span class='hs-varid'>x</span>		<span class='hs-keyglyph'>=</span> <span class='hs-varid'>aggregate</span> <span class='hs-conid'>AggrCount</span> <span class='hs-varid'>x</span>
<a name="line-696"></a>
<a name="line-697"></a><span class='hs-comment'>-- | Returns the total sum of a column.</span>
<a name="line-698"></a><span class='hs-sel'>_sum</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Num</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-varid'>a</span>
<a name="line-699"></a><span class='hs-sel'>_sum</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>aggregate</span> <span class='hs-conid'>AggrSum</span> <span class='hs-varid'>x</span>
<a name="line-700"></a>
<a name="line-701"></a><span class='hs-comment'>-- | Returns the highest value of a column.</span>
<a name="line-702"></a><span class='hs-sel'>_max</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Ord</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-varid'>a</span>
<a name="line-703"></a><span class='hs-sel'>_max</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>aggregate</span> <span class='hs-conid'>AggrMax</span> <span class='hs-varid'>x</span>
<a name="line-704"></a>
<a name="line-705"></a><span class='hs-comment'>-- | Returns the lowest value of a column.</span>
<a name="line-706"></a><span class='hs-sel'>_min</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Ord</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-varid'>a</span>
<a name="line-707"></a><span class='hs-sel'>_min</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>aggregate</span> <span class='hs-conid'>AggrMin</span> <span class='hs-varid'>x</span>
<a name="line-708"></a>
<a name="line-709"></a><a name="avg"></a><span class='hs-comment'>-- | Returns the average of a column.</span>
<a name="line-710"></a><span class='hs-definition'>avg</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Num</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-varid'>a</span>
<a name="line-711"></a><span class='hs-definition'>avg</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>aggregate</span> <span class='hs-conid'>AggrAvg</span> <span class='hs-varid'>x</span>
<a name="line-712"></a>
<a name="line-713"></a><a name="stddev"></a><span class='hs-comment'>-- | Returns the standard deviation of a column.</span>
<a name="line-714"></a><span class='hs-definition'>stddev</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Num</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-varid'>a</span>
<a name="line-715"></a><span class='hs-definition'>stddev</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>aggregate</span> <span class='hs-conid'>AggrStdDev</span> <span class='hs-varid'>x</span>
<a name="line-716"></a>
<a name="line-717"></a><a name="stddevP"></a><span class='hs-definition'>stddevP</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Num</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-varid'>a</span>
<a name="line-718"></a><span class='hs-definition'>stddevP</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>aggregate</span> <span class='hs-conid'>AggrStdDevP</span> <span class='hs-varid'>x</span>
<a name="line-719"></a>
<a name="line-720"></a><a name="variance"></a><span class='hs-comment'>-- | Returns the standard variance of a column.</span>
<a name="line-721"></a><span class='hs-definition'>variance</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Num</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-varid'>a</span>
<a name="line-722"></a><span class='hs-definition'>variance</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>aggregate</span> <span class='hs-conid'>AggrVar</span> <span class='hs-varid'>x</span>
<a name="line-723"></a>
<a name="line-724"></a><a name="varianceP"></a><span class='hs-definition'>varianceP</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Num</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>ExprAggr</span> <span class='hs-varid'>a</span>
<a name="line-725"></a><span class='hs-definition'>varianceP</span> <span class='hs-varid'>x</span>  <span class='hs-keyglyph'>=</span> <span class='hs-varid'>aggregate</span> <span class='hs-conid'>AggrVarP</span> <span class='hs-varid'>x</span>
<a name="line-726"></a>
<a name="line-727"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-728"></a><span class='hs-comment'>-- Special ops</span>
<a name="line-729"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-730"></a>
<a name="line-731"></a><a name="top"></a><span class='hs-comment'>-- | Return the n topmost records.</span>
<a name="line-732"></a><span class='hs-definition'>top</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-conid'>()</span>
<a name="line-733"></a><span class='hs-definition'>top</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>updatePrimQuery_</span> <span class='hs-layout'>(</span><span class='hs-conid'>Special</span> <span class='hs-layout'>(</span><span class='hs-conid'>Top</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-734"></a>
<a name="line-735"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-736"></a><span class='hs-comment'>-- Ordering results</span>
<a name="line-737"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-738"></a>
<a name="line-739"></a><a name="orderOp"></a><span class='hs-definition'>orderOp</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>HasField</span> <span class='hs-varid'>f</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>OrderOp</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Attr</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>OrderExpr</span>
<a name="line-740"></a><span class='hs-definition'>orderOp</span> <span class='hs-varid'>op</span> <span class='hs-varid'>rel</span> <span class='hs-varid'>attr</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>OrderExpr</span> <span class='hs-varid'>op</span> <span class='hs-varid'>expr</span>
<a name="line-741"></a>    <span class='hs-keyword'>where</span> <span class='hs-conid'>Expr</span> <span class='hs-varid'>expr</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>select</span> <span class='hs-varid'>attr</span> <span class='hs-varid'>rel</span>
<a name="line-742"></a>
<a name="line-743"></a><a name="asc"></a><span class='hs-comment'>-- | Use this together with the function 'order' to </span>
<a name="line-744"></a><span class='hs-comment'>-- order the results of a query in ascending order.</span>
<a name="line-745"></a><span class='hs-comment'>-- Takes a relation and an attribute of that relation, which</span>
<a name="line-746"></a><span class='hs-comment'>-- is used for the ordering.</span>
<a name="line-747"></a><span class='hs-definition'>asc</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>HasField</span> <span class='hs-varid'>f</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Attr</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>OrderExpr</span>
<a name="line-748"></a><span class='hs-definition'>asc</span> <span class='hs-varid'>rel</span> <span class='hs-varid'>attr</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>orderOp</span> <span class='hs-conid'>OpAsc</span> <span class='hs-varid'>rel</span> <span class='hs-varid'>attr</span>
<a name="line-749"></a>
<a name="line-750"></a><a name="desc"></a><span class='hs-comment'>-- | Use this together with the function 'order' to </span>
<a name="line-751"></a><span class='hs-comment'>-- order the results of a query in descending order.</span>
<a name="line-752"></a><span class='hs-comment'>-- Takes a relation and an attribute of that relation, which</span>
<a name="line-753"></a><span class='hs-comment'>-- is used for the ordering.</span>
<a name="line-754"></a><span class='hs-definition'>desc</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>HasField</span> <span class='hs-varid'>f</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Attr</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>OrderExpr</span>
<a name="line-755"></a><span class='hs-definition'>desc</span> <span class='hs-varid'>rel</span> <span class='hs-varid'>attr</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>orderOp</span> <span class='hs-conid'>OpDesc</span> <span class='hs-varid'>rel</span> <span class='hs-varid'>attr</span>
<a name="line-756"></a>
<a name="line-757"></a><a name="order"></a><span class='hs-comment'>-- | Order the results of a query.</span>
<a name="line-758"></a><span class='hs-comment'>-- Use this with the 'asc' or 'desc' functions.</span>
<a name="line-759"></a><span class='hs-definition'>order</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>OrderExpr</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-conid'>()</span>
<a name="line-760"></a><span class='hs-definition'>order</span> <span class='hs-varid'>xs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>updatePrimQuery_</span> <span class='hs-layout'>(</span><span class='hs-conid'>Special</span> <span class='hs-layout'>(</span><span class='hs-conid'>Order</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-761"></a>
<a name="line-762"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-763"></a><span class='hs-comment'>-- Query Monad</span>
<a name="line-764"></a><span class='hs-comment'>-----------------------------------------------------------</span>
<a name="line-765"></a>
<a name="line-766"></a><a name="unQuery"></a><span class='hs-definition'>unQuery</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Query</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-varid'>a</span>
<a name="line-767"></a><span class='hs-definition'>unQuery</span> <span class='hs-layout'>(</span><span class='hs-conid'>Query</span> <span class='hs-varid'>g</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fst</span> <span class='hs-varop'>$</span> <span class='hs-varid'>g</span> <span class='hs-layout'>(</span><span class='hs-num'>1</span><span class='hs-layout'>,</span> <span class='hs-conid'>Empty</span><span class='hs-layout'>)</span>
<a name="line-768"></a>
<a name="line-769"></a><a name="runQuery"></a><span class='hs-definition'>runQuery</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>PrimQuery</span>
<a name="line-770"></a><span class='hs-definition'>runQuery</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fst</span> <span class='hs-varop'>.</span> <span class='hs-varid'>runQueryRel</span>
<a name="line-771"></a>
<a name="line-772"></a><a name="runQueryRel"></a><span class='hs-definition'>runQueryRel</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-layout'>(</span><span class='hs-conid'>PrimQuery</span><span class='hs-layout'>,</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-773"></a><span class='hs-definition'>runQueryRel</span> <span class='hs-layout'>(</span><span class='hs-conid'>Query</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span>
<a name="line-774"></a>        <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>alias</span> <span class='hs-varid'>scheme</span><span class='hs-layout'>,</span><span class='hs-layout'>(</span><span class='hs-varid'>i</span><span class='hs-layout'>,</span><span class='hs-varid'>primQuery</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-num'>1</span><span class='hs-layout'>,</span><span class='hs-conid'>Empty</span><span class='hs-layout'>)</span>
<a name="line-775"></a>              <span class='hs-varid'>assoc</span>   <span class='hs-keyglyph'>=</span> <span class='hs-varid'>zip</span> <span class='hs-varid'>scheme</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-layout'>(</span><span class='hs-conid'>AttrExpr</span> <span class='hs-varop'>.</span> <span class='hs-varid'>fresh</span> <span class='hs-varid'>alias</span><span class='hs-layout'>)</span> <span class='hs-varid'>scheme</span><span class='hs-layout'>)</span>
<a name="line-776"></a>          <span class='hs-keyword'>in</span>  <span class='hs-layout'>(</span><span class='hs-conid'>Project</span> <span class='hs-varid'>assoc</span> <span class='hs-varid'>primQuery</span><span class='hs-layout'>,</span> <span class='hs-conid'>Rel</span> <span class='hs-num'>0</span> <span class='hs-varid'>scheme</span><span class='hs-layout'>)</span>
<a name="line-777"></a>
<a name="line-778"></a><a name="subQuery"></a><span class='hs-comment'>-- | Allows a subquery to be created between another query and</span>
<a name="line-779"></a><span class='hs-comment'>-- this query. Normally query definition is associative and query definition</span>
<a name="line-780"></a><span class='hs-comment'>-- is interleaved. This combinator ensures the given query is</span>
<a name="line-781"></a><span class='hs-comment'>-- added as a whole piece.</span>
<a name="line-782"></a><span class='hs-definition'>subQuery</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-783"></a><span class='hs-definition'>subQuery</span> <span class='hs-layout'>(</span><span class='hs-conid'>Query</span> <span class='hs-varid'>qs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Query</span> <span class='hs-varid'>make</span>
<a name="line-784"></a>  <span class='hs-keyword'>where</span>
<a name="line-785"></a>    <span class='hs-varid'>make</span> <span class='hs-layout'>(</span><span class='hs-varid'>currentAlias</span><span class='hs-layout'>,</span> <span class='hs-varid'>currentQry</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-786"></a>        <span class='hs-comment'>-- Take the query to add and run it first, using the current alias as</span>
<a name="line-787"></a>        <span class='hs-comment'>-- a seed.</span>
<a name="line-788"></a>        <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>otherAlias</span> <span class='hs-varid'>otherScheme</span><span class='hs-layout'>,</span><span class='hs-layout'>(</span><span class='hs-varid'>newestAlias</span><span class='hs-layout'>,</span> <span class='hs-varid'>otherQuery</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>qs</span> <span class='hs-layout'>(</span><span class='hs-varid'>currentAlias</span><span class='hs-layout'>,</span><span class='hs-conid'>Empty</span><span class='hs-layout'>)</span>
<a name="line-789"></a>            <span class='hs-comment'>-- Effectively renames all columns in otherQuery to make them unique in this</span>
<a name="line-790"></a>            <span class='hs-comment'>-- query.</span>
<a name="line-791"></a>            <span class='hs-varid'>assoc</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>zip</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-layout'>(</span><span class='hs-varid'>fresh</span> <span class='hs-varid'>newestAlias</span><span class='hs-layout'>)</span> <span class='hs-varid'>otherScheme</span><span class='hs-layout'>)</span>
<a name="line-792"></a>                        <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-layout'>(</span><span class='hs-conid'>AttrExpr</span> <span class='hs-varop'>.</span> <span class='hs-varid'>fresh</span> <span class='hs-varid'>otherAlias</span><span class='hs-layout'>)</span> <span class='hs-varid'>otherScheme</span><span class='hs-layout'>)</span>
<a name="line-793"></a>            <span class='hs-comment'>-- Produce a query which is a cross product of the other query and the current query.</span>
<a name="line-794"></a>        <span class='hs-keyword'>in</span> <span class='hs-layout'>(</span><span class='hs-conid'>Rel</span> <span class='hs-varid'>newestAlias</span> <span class='hs-varid'>otherScheme</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varid'>newestAlias</span> <span class='hs-varop'>+</span> <span class='hs-num'>1</span><span class='hs-layout'>,</span> <span class='hs-varid'>times</span> <span class='hs-layout'>(</span><span class='hs-conid'>Project</span> <span class='hs-varid'>assoc</span> <span class='hs-varid'>otherQuery</span><span class='hs-layout'>)</span> <span class='hs-varid'>currentQry</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-795"></a>            
<a name="line-796"></a><a name="instance%20Functor%20Query"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Functor</span> <span class='hs-conid'>Query</span> <span class='hs-keyword'>where</span>
<a name="line-797"></a>  <span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>Query</span> <span class='hs-varid'>g</span><span class='hs-layout'>)</span>      <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>q0</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-layout'>,</span><span class='hs-varid'>q1</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>g</span> <span class='hs-varid'>q0</span>  <span class='hs-keyword'>in</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>x</span><span class='hs-layout'>,</span><span class='hs-varid'>q1</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-798"></a>
<a name="line-799"></a><a name="instance%20Monad%20Query"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-conid'>Query</span> <span class='hs-keyword'>where</span>
<a name="line-800"></a>  <span class='hs-varid'>return</span> <span class='hs-varid'>x</span>              <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>q0</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-layout'>,</span><span class='hs-varid'>q0</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-801"></a>  <span class='hs-layout'>(</span><span class='hs-conid'>Query</span> <span class='hs-varid'>g</span><span class='hs-layout'>)</span> <span class='hs-varop'>&gt;&gt;=</span> <span class='hs-varid'>f</span>       <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>q0</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-layout'>,</span><span class='hs-varid'>q1</span><span class='hs-layout'>)</span>    <span class='hs-keyglyph'>=</span> <span class='hs-varid'>g</span> <span class='hs-varid'>q0</span>
<a name="line-802"></a>                                            <span class='hs-layout'>(</span><span class='hs-conid'>Query</span> <span class='hs-varid'>h</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varid'>x</span>
<a name="line-803"></a>                                        <span class='hs-keyword'>in</span>  <span class='hs-layout'>(</span><span class='hs-varid'>h</span> <span class='hs-varid'>q1</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-804"></a>
<a name="line-805"></a><a name="updatePrimQuery"></a><span class='hs-definition'>updatePrimQuery</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>PrimQuery</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>PrimQuery</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-conid'>PrimQuery</span>
<a name="line-806"></a><span class='hs-definition'>updatePrimQuery</span> <span class='hs-varid'>f</span>  <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-varid'>i</span><span class='hs-layout'>,</span><span class='hs-varid'>qt</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-layout'>(</span><span class='hs-varid'>qt</span><span class='hs-layout'>,</span><span class='hs-layout'>(</span><span class='hs-varid'>i</span><span class='hs-layout'>,</span><span class='hs-varid'>f</span> <span class='hs-varid'>qt</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-807"></a>
<a name="line-808"></a><a name="updatePrimQuery_"></a><span class='hs-definition'>updatePrimQuery_</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>PrimQuery</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>PrimQuery</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Query</span> <span class='hs-conid'>()</span>
<a name="line-809"></a><span class='hs-definition'>updatePrimQuery_</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>updatePrimQuery</span> <span class='hs-varid'>f</span> <span class='hs-varop'>&gt;&gt;</span> <span class='hs-varid'>return</span> <span class='hs-conid'>()</span>
<a name="line-810"></a>
<a name="line-811"></a><a name="newAlias"></a><span class='hs-definition'>newAlias</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Query</span> <span class='hs-conid'>Alias</span>
<a name="line-812"></a><span class='hs-definition'>newAlias</span>                <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Query</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-varid'>i</span><span class='hs-layout'>,</span><span class='hs-varid'>qt</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-layout'>(</span><span class='hs-varid'>i</span><span class='hs-layout'>,</span><span class='hs-layout'>(</span><span class='hs-varid'>i</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>,</span><span class='hs-varid'>qt</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-813"></a>
<a name="line-814"></a><a name="fresh"></a><span class='hs-comment'>-- fresh 0 is used in the 'Database' module</span>
<a name="line-815"></a><span class='hs-definition'>fresh</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Alias</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Attribute</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-conid'>Attribute</span>
<a name="line-816"></a><span class='hs-definition'>fresh</span> <span class='hs-num'>0</span>     <span class='hs-varid'>attribute</span>   <span class='hs-keyglyph'>=</span> <span class='hs-varid'>attribute</span>
<a name="line-817"></a><span class='hs-definition'>fresh</span> <span class='hs-varid'>alias</span> <span class='hs-varid'>attribute</span>   <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>attribute</span> <span class='hs-varop'>++</span> <span class='hs-varid'>show</span> <span class='hs-varid'>alias</span><span class='hs-layout'>)</span>
<a name="line-818"></a>
<a name="line-819"></a><a name="labels"></a><span class='hs-definition'>labels</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ShowLabels</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>String</span><span class='hs-keyglyph'>]</span>
<a name="line-820"></a><span class='hs-definition'>labels</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>recordLabels</span>
<a name="line-821"></a>
<a name="line-822"></a><a name="exprs"></a><span class='hs-comment'>-- Type safe version of exprs below. If we use this, we must add</span>
<a name="line-823"></a><span class='hs-comment'>--  ToPrimExprs r to a lot of functions</span>
<a name="line-824"></a><span class='hs-definition'>exprs</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ToPrimExprs</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>Record</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>PrimExpr</span><span class='hs-keyglyph'>]</span>
<a name="line-825"></a><span class='hs-definition'>exprs</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>toPrimExprs</span> <span class='hs-layout'>(</span><span class='hs-varid'>r</span> <span class='hs-conid'>RecNil</span><span class='hs-layout'>)</span>
<a name="line-826"></a>
<a name="line-827"></a><a name="ToPrimExprs"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>ToPrimExprs</span> <span class='hs-varid'>r</span> <span class='hs-keyword'>where</span>
<a name="line-828"></a>    <span class='hs-varid'>toPrimExprs</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-&gt;</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>PrimExpr</span><span class='hs-keyglyph'>]</span>
<a name="line-829"></a>
<a name="line-830"></a><a name="instance%20ToPrimExprs%20RecNil"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ToPrimExprs</span> <span class='hs-conid'>RecNil</span> <span class='hs-keyword'>where</span>
<a name="line-831"></a>    <span class='hs-varid'>toPrimExprs</span> <span class='hs-keyglyph'>~</span><span class='hs-conid'>RecNil</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>[]</span>
<a name="line-832"></a>
<a name="line-833"></a><a name="instance%20ToPrimExprs%20(RecCons%20l%20(e%20a)%20r)"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>ExprC</span> <span class='hs-varid'>e</span><span class='hs-layout'>,</span> <span class='hs-conid'>ToPrimExprs</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=&gt;</span> <span class='hs-conid'>ToPrimExprs</span> <span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>l</span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-834"></a>    <span class='hs-varid'>toPrimExprs</span> <span class='hs-keyglyph'>~</span><span class='hs-layout'>(</span><span class='hs-conid'>RecCons</span> <span class='hs-varid'>e</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>primExpr</span> <span class='hs-varid'>e</span> <span class='hs-conop'>:</span> <span class='hs-varid'>toPrimExprs</span> <span class='hs-varid'>r</span>
<a name="line-835"></a>
</pre></body>
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