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<pre><a name="line-1"></a><span class='hs-comment'>{-# OPTIONS_GHC -cpp #-}</span>
<a name="line-2"></a><span class='hs-comment'>-----------------------------------------------------------------------------</span>
<a name="line-3"></a><span class='hs-comment'>-- |</span>
<a name="line-4"></a><span class='hs-comment'>-- Module : System.Console.SimpleLineEditor</span>
<a name="line-5"></a><span class='hs-comment'>-- Copyright : (c) 2000,2003, Malcolm Wallace</span>
<a name="line-6"></a><span class='hs-comment'>-- License : GPL (if it depends on readline, which is GPL)</span>
<a name="line-7"></a><span class='hs-comment'>-- BSD (otherwise)</span>
<a name="line-8"></a><span class='hs-comment'>--</span>
<a name="line-9"></a><span class='hs-comment'>-- Maintainer : libraries@haskell.org</span>
<a name="line-10"></a><span class='hs-comment'>-- Stability : experimental</span>
<a name="line-11"></a><span class='hs-comment'>-- Portability : non-portable (unix-specific at the moment)</span>
<a name="line-12"></a><span class='hs-comment'>--</span>
<a name="line-13"></a><span class='hs-comment'>-- A simple line editor, using the GNU readline library if available,</span>
<a name="line-14"></a><span class='hs-comment'>-- or a small emulation otherwise.</span>
<a name="line-15"></a><span class='hs-comment'>--</span>
<a name="line-16"></a><span class='hs-comment'>-----------------------------------------------------------------------------</span>
<a name="line-17"></a>
<a name="line-18"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>Console</span><span class='hs-varop'>.</span><span class='hs-conid'>SimpleLineEditor</span>
<a name="line-19"></a> <span class='hs-layout'>(</span> <span class='hs-varid'>initialise</span> <span class='hs-comment'>-- :: IO ()</span>
<a name="line-20"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>restore</span> <span class='hs-comment'>-- :: IO ()</span>
<a name="line-21"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>getLineEdited</span> <span class='hs-comment'>-- :: String -> IO (Maybe String)</span>
<a name="line-22"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>delChars</span> <span class='hs-comment'>-- :: String -> IO ()</span>
<a name="line-23"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-24"></a>
<a name="line-25"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-varid'>stdin</span><span class='hs-layout'>,</span> <span class='hs-varid'>stdout</span><span class='hs-layout'>,</span> <span class='hs-conid'>BufferMode</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-varid'>hSetBuffering</span><span class='hs-layout'>)</span>
<a name="line-26"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span> <span class='hs-layout'>(</span><span class='hs-varid'>when</span><span class='hs-layout'>)</span>
<a name="line-27"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Char</span> <span class='hs-layout'>(</span><span class='hs-varid'>isSpace</span><span class='hs-layout'>)</span>
<a name="line-28"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-varid'>isJust</span><span class='hs-layout'>,</span> <span class='hs-varid'>fromJust</span><span class='hs-layout'>)</span>
<a name="line-29"></a><span class='hs-cpp'>#if USE_READLINE</span>
<a name="line-30"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>Console</span><span class='hs-varop'>.</span><span class='hs-conid'>Readline</span>
<a name="line-31"></a><span class='hs-cpp'>#else</span>
<a name="line-32"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>IORef</span> <span class='hs-layout'>(</span><span class='hs-conid'>IORef</span><span class='hs-layout'>,</span> <span class='hs-varid'>newIORef</span><span class='hs-layout'>,</span> <span class='hs-varid'>readIORef</span><span class='hs-layout'>,</span> <span class='hs-varid'>writeIORef</span><span class='hs-layout'>)</span>
<a name="line-33"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>Cmd</span> <span class='hs-layout'>(</span><span class='hs-varid'>system</span><span class='hs-layout'>)</span>
<a name="line-34"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-varid'>hGetChar</span><span class='hs-layout'>)</span>
<a name="line-35"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span><span class='hs-varop'>.</span><span class='hs-conid'>Unsafe</span> <span class='hs-layout'>(</span><span class='hs-varid'>unsafePerformIO</span><span class='hs-layout'>)</span>
<a name="line-36"></a><span class='hs-cpp'>#endif</span>
<a name="line-37"></a>
<a name="line-38"></a><a name="initialise"></a><span class='hs-comment'>-- | Set up the environment so that the terminal passes characters directly</span>
<a name="line-39"></a><span class='hs-comment'>-- into the Haskell program, for immediate interpretation by the line editor.</span>
<a name="line-40"></a><span class='hs-definition'>initialise</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IO</span> <span class='hs-conid'>()</span>
<a name="line-41"></a><span class='hs-definition'>initialise</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-42"></a> <span class='hs-varid'>hSetBuffering</span> <span class='hs-varid'>stdout</span> <span class='hs-conid'>NoBuffering</span>
<a name="line-43"></a> <span class='hs-varid'>hSetBuffering</span> <span class='hs-varid'>stdin</span> <span class='hs-conid'>NoBuffering</span>
<a name="line-44"></a><span class='hs-cpp'>#if USE_READLINE</span>
<a name="line-45"></a> <span class='hs-varid'>initialize</span>
<a name="line-46"></a><span class='hs-cpp'>#else</span>
<a name="line-47"></a> <span class='hs-comment'>-- The following call is probably non-portable. Better suggestions?</span>
<a name="line-48"></a> <span class='hs-comment'>-- Note, we turn OFF terminal echoing of input characters</span>
<a name="line-49"></a> <span class='hs-varid'>system</span><span class='hs-layout'>(</span><span class='hs-str'>"stty -icanon min 1 -echo"</span><span class='hs-layout'>)</span>
<a name="line-50"></a> <span class='hs-varid'>return</span> <span class='hs-conid'>()</span>
<a name="line-51"></a><span class='hs-cpp'>#endif</span>
<a name="line-52"></a>
<a name="line-53"></a><a name="restore"></a><span class='hs-comment'>-- | Restore the environment so that the terminal is usable in normal</span>
<a name="line-54"></a><span class='hs-comment'>-- mode once again.</span>
<a name="line-55"></a><span class='hs-definition'>restore</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IO</span> <span class='hs-conid'>()</span>
<a name="line-56"></a><span class='hs-definition'>restore</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-57"></a> <span class='hs-varid'>hSetBuffering</span> <span class='hs-varid'>stdout</span> <span class='hs-conid'>LineBuffering</span>
<a name="line-58"></a> <span class='hs-varid'>hSetBuffering</span> <span class='hs-varid'>stdin</span> <span class='hs-conid'>LineBuffering</span>
<a name="line-59"></a><span class='hs-cpp'>#if ! USE_READLINE</span>
<a name="line-60"></a> <span class='hs-comment'>-- The following call is probably non-portable. Better suggestions?</span>
<a name="line-61"></a> <span class='hs-comment'>-- We assume the terminal should echo input characters after restoration</span>
<a name="line-62"></a> <span class='hs-varid'>system</span><span class='hs-layout'>(</span><span class='hs-str'>"stty icanon echo"</span><span class='hs-layout'>)</span>
<a name="line-63"></a> <span class='hs-varid'>return</span> <span class='hs-conid'>()</span>
<a name="line-64"></a><span class='hs-cpp'>#endif</span>
<a name="line-65"></a>
<a name="line-66"></a><a name="delChars"></a><span class='hs-comment'>-- | Remove the given string from immediately behind (to the left of) the</span>
<a name="line-67"></a><span class='hs-comment'>-- current cursor position.</span>
<a name="line-68"></a><span class='hs-definition'>delChars</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-conid'>()</span>
<a name="line-69"></a><span class='hs-definition'>delChars</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span> <span class='hs-conid'>()</span>
<a name="line-70"></a><span class='hs-definition'>delChars</span> <span class='hs-layout'>(</span><span class='hs-keyword'>_</span><span class='hs-conop'>:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <span class='hs-varid'>putStr</span> <span class='hs-str'>"\BS \BS"</span>
<a name="line-71"></a> <span class='hs-varid'>delChars</span> <span class='hs-varid'>xs</span>
<a name="line-72"></a>
<a name="line-73"></a><span class='hs-comment'>-- | 'getLineEdited p' uses the string @p@ as a prompt, and returns a line</span>
<a name="line-74"></a><span class='hs-comment'>-- of input from the user. The user can edit the line in-place before</span>
<a name="line-75"></a><span class='hs-comment'>-- completion, using common readline-like command keys. (The real readline</span>
<a name="line-76"></a><span class='hs-comment'>-- is used when available, or otherwise a simplified emulation.)</span>
<a name="line-77"></a>
<a name="line-78"></a><span class='hs-cpp'>#if USE_READLINE</span>
<a name="line-79"></a>
<a name="line-80"></a><a name="getLineEdited"></a><span class='hs-definition'>getLineEdited</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span>
<a name="line-81"></a><span class='hs-definition'>getLineEdited</span> <span class='hs-varid'>prompt</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-82"></a> <span class='hs-varid'>ms</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>readline</span> <span class='hs-varid'>prompt</span>
<a name="line-83"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>ms</span> <span class='hs-keyword'>of</span>
<a name="line-84"></a> <span class='hs-conid'>Nothing</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varid'>ms</span>
<a name="line-85"></a> <span class='hs-conid'>Just</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>when</span> <span class='hs-layout'>(</span><span class='hs-varid'>not</span> <span class='hs-layout'>(</span><span class='hs-varid'>all</span> <span class='hs-varid'>isSpace</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>addHistory</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-varop'>>></span> <span class='hs-varid'>return</span> <span class='hs-varid'>ms</span>
<a name="line-86"></a>
<a name="line-87"></a><span class='hs-cpp'>#else</span>
<a name="line-88"></a>
<a name="line-89"></a><a name="history"></a><span class='hs-comment'>-- nasty imperative state holds the command history</span>
<a name="line-90"></a><span class='hs-definition'>history</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IORef</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>String</span><span class='hs-keyglyph'>]</span>
<a name="line-91"></a><span class='hs-definition'>history</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>unsafePerformIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>newIORef</span> <span class='hs-conid'>[]</span><span class='hs-layout'>)</span>
<a name="line-92"></a>
<a name="line-93"></a><span class='hs-definition'>getLineEdited</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span>
<a name="line-94"></a><span class='hs-definition'>getLineEdited</span> <span class='hs-varid'>prompt</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-95"></a> <span class='hs-varid'>putStr</span> <span class='hs-varid'>prompt</span>
<a name="line-96"></a> <span class='hs-varid'>previous</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>readIORef</span> <span class='hs-varid'>history</span>
<a name="line-97"></a> <span class='hs-varid'>ms</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>gl</span> <span class='hs-str'>""</span> <span class='hs-num'>0</span> <span class='hs-layout'>(</span><span class='hs-conid'>[]</span><span class='hs-layout'>,</span><span class='hs-varid'>previous</span><span class='hs-layout'>)</span>
<a name="line-98"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>ms</span> <span class='hs-keyword'>of</span>
<a name="line-99"></a> <span class='hs-conid'>Nothing</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varid'>ms</span>
<a name="line-100"></a> <span class='hs-conid'>Just</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-varid'>when</span> <span class='hs-layout'>(</span><span class='hs-varid'>not</span> <span class='hs-layout'>(</span><span class='hs-varid'>all</span> <span class='hs-varid'>isSpace</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-101"></a> <span class='hs-layout'>(</span><span class='hs-varid'>writeIORef</span> <span class='hs-varid'>history</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-varid'>s</span><span class='hs-conop'>:</span> <span class='hs-varid'>previous</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-102"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>ms</span>
<a name="line-103"></a> <span class='hs-keyword'>where</span>
<a name="line-104"></a> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-num'>0</span> <span class='hs-varid'>hist</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <span class='hs-comment'>-- s is accumulated line (in reverse)</span>
<a name="line-105"></a> <span class='hs-comment'>-- 0 is cursor position FROM THE END of the string</span>
<a name="line-106"></a> <span class='hs-varid'>cmd</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lineCmd</span>
<a name="line-107"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>cmd</span> <span class='hs-keyword'>of</span>
<a name="line-108"></a> <span class='hs-conid'>Char</span> <span class='hs-varid'>c</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>putChar</span> <span class='hs-varid'>c</span> <span class='hs-varop'>>></span> <span class='hs-varid'>gl</span> <span class='hs-layout'>(</span><span class='hs-varid'>c</span><span class='hs-conop'>:</span><span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-num'>0</span> <span class='hs-varid'>hist</span>
<a name="line-109"></a> <span class='hs-conid'>Accept</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Just</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-110"></a> <span class='hs-conid'>Cancel</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>Nothing</span>
<a name="line-111"></a> <span class='hs-conid'>Delete</span> <span class='hs-conid'>L</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>if</span> <span class='hs-varid'>null</span> <span class='hs-varid'>s</span> <span class='hs-keyword'>then</span> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-num'>0</span> <span class='hs-varid'>hist</span>
<a name="line-112"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>delChars</span> <span class='hs-str'>"_"</span> <span class='hs-varop'>>></span> <span class='hs-varid'>gl</span> <span class='hs-layout'>(</span><span class='hs-varid'>tail</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-num'>0</span> <span class='hs-varid'>hist</span>
<a name="line-113"></a> <span class='hs-conid'>Delete</span> <span class='hs-conid'>Begin</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>delChars</span> <span class='hs-varid'>s</span> <span class='hs-varop'>>></span> <span class='hs-varid'>gl</span> <span class='hs-str'>""</span> <span class='hs-num'>0</span> <span class='hs-varid'>hist</span>
<a name="line-114"></a> <span class='hs-conid'>Move</span> <span class='hs-conid'>L</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>if</span> <span class='hs-varid'>not</span> <span class='hs-layout'>(</span><span class='hs-varid'>null</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyword'>then</span> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-str'>"\BS"</span><span class='hs-layout'>)</span> <span class='hs-varop'>>></span> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-num'>1</span> <span class='hs-varid'>hist</span>
<a name="line-115"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-num'>0</span> <span class='hs-varid'>hist</span>
<a name="line-116"></a> <span class='hs-conid'>History</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>hist</span> <span class='hs-keyword'>of</span>
<a name="line-117"></a> <span class='hs-layout'>(</span><span class='hs-sel'>_fut</span><span class='hs-layout'>,</span> <span class='hs-conid'>[]</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-num'>0</span> <span class='hs-varid'>hist</span>
<a name="line-118"></a> <span class='hs-layout'>(</span><span class='hs-varid'>fut</span><span class='hs-layout'>,</span> <span class='hs-varid'>p</span><span class='hs-conop'>:</span><span class='hs-varid'>past</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-varid'>delChars</span> <span class='hs-varid'>s</span>
<a name="line-119"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span>
<a name="line-120"></a> <span class='hs-varid'>gl</span> <span class='hs-varid'>p</span> <span class='hs-num'>0</span> <span class='hs-layout'>(</span><span class='hs-varid'>s</span><span class='hs-conop'>:</span><span class='hs-varid'>fut</span><span class='hs-layout'>,</span> <span class='hs-varid'>past</span><span class='hs-layout'>)</span>
<a name="line-121"></a> <span class='hs-conid'>Future</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>hist</span> <span class='hs-keyword'>of</span>
<a name="line-122"></a> <span class='hs-layout'>(</span><span class='hs-conid'>[]</span><span class='hs-layout'>,</span> <span class='hs-sel'>_past</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-num'>0</span> <span class='hs-varid'>hist</span>
<a name="line-123"></a> <span class='hs-layout'>(</span><span class='hs-varid'>f</span><span class='hs-conop'>:</span><span class='hs-varid'>fut</span><span class='hs-layout'>,</span> <span class='hs-varid'>past</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-varid'>delChars</span> <span class='hs-varid'>s</span>
<a name="line-124"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span>
<a name="line-125"></a> <span class='hs-varid'>gl</span> <span class='hs-varid'>f</span> <span class='hs-num'>0</span> <span class='hs-layout'>(</span><span class='hs-varid'>fut</span><span class='hs-layout'>,</span> <span class='hs-varid'>s</span><span class='hs-conop'>:</span><span class='hs-varid'>past</span><span class='hs-layout'>)</span>
<a name="line-126"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-num'>0</span> <span class='hs-varid'>hist</span>
<a name="line-127"></a>
<a name="line-128"></a> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-varid'>n</span> <span class='hs-varid'>hist</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <span class='hs-comment'>-- s is accumulated line, n(/=0) is cursor position</span>
<a name="line-129"></a> <span class='hs-varid'>cmd</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lineCmd</span>
<a name="line-130"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>cmd</span> <span class='hs-keyword'>of</span>
<a name="line-131"></a> <span class='hs-conid'>Char</span> <span class='hs-varid'>c</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>c</span><span class='hs-conop'>:</span> <span class='hs-varid'>reverse</span> <span class='hs-layout'>(</span><span class='hs-varid'>take</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-132"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>replicate</span> <span class='hs-varid'>n</span> <span class='hs-chr'>'\BS'</span><span class='hs-layout'>)</span>
<a name="line-133"></a> <span class='hs-varid'>gl</span> <span class='hs-layout'>(</span><span class='hs-varid'>take</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span> <span class='hs-varop'>++</span> <span class='hs-varid'>c</span><span class='hs-conop'>:</span> <span class='hs-varid'>drop</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-varid'>n</span> <span class='hs-varid'>hist</span>
<a name="line-134"></a> <span class='hs-conid'>Accept</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Just</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-135"></a> <span class='hs-conid'>Cancel</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>Nothing</span>
<a name="line-136"></a> <span class='hs-conid'>Move</span> <span class='hs-conid'>R</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-keyword'>let</span> <span class='hs-varid'>n1</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>n</span><span class='hs-comment'>-</span><span class='hs-num'>1</span>
<a name="line-137"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-layout'>(</span><span class='hs-varid'>take</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-varop'>++</span><span class='hs-str'>" "</span><span class='hs-layout'>)</span>
<a name="line-138"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>replicate</span> <span class='hs-varid'>n</span> <span class='hs-chr'>'\BS'</span><span class='hs-layout'>)</span>
<a name="line-139"></a> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-varid'>n1</span> <span class='hs-varid'>hist</span>
<a name="line-140"></a> <span class='hs-conid'>Delete</span> <span class='hs-conid'>R</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-keyword'>let</span> <span class='hs-varid'>n1</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>n</span><span class='hs-comment'>-</span><span class='hs-num'>1</span>
<a name="line-141"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-layout'>(</span><span class='hs-varid'>take</span> <span class='hs-varid'>n1</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-varop'>++</span> <span class='hs-str'>" "</span><span class='hs-layout'>)</span>
<a name="line-142"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>replicate</span> <span class='hs-layout'>(</span><span class='hs-varid'>n1</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-chr'>'\BS'</span><span class='hs-layout'>)</span>
<a name="line-143"></a> <span class='hs-varid'>gl</span> <span class='hs-layout'>(</span><span class='hs-varid'>take</span> <span class='hs-varid'>n1</span> <span class='hs-varid'>s</span> <span class='hs-varop'>++</span> <span class='hs-varid'>drop</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-varid'>n1</span> <span class='hs-varid'>hist</span>
<a name="line-144"></a> <span class='hs-conid'>Move</span> <span class='hs-conid'>L</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-keyword'>let</span> <span class='hs-varid'>n1</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>n</span><span class='hs-varop'>+</span><span class='hs-num'>1</span>
<a name="line-145"></a> <span class='hs-keyword'>if</span> <span class='hs-varid'>n1</span> <span class='hs-varop'><=</span> <span class='hs-varid'>length</span> <span class='hs-varid'>s</span> <span class='hs-keyword'>then</span> <span class='hs-keyword'>do</span>
<a name="line-146"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-chr'>'\BS'</span><span class='hs-conop'>:</span><span class='hs-varid'>reverse</span> <span class='hs-layout'>(</span><span class='hs-varid'>take</span> <span class='hs-varid'>n1</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-147"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>replicate</span> <span class='hs-varid'>n1</span> <span class='hs-chr'>'\BS'</span><span class='hs-layout'>)</span>
<a name="line-148"></a> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-varid'>n1</span> <span class='hs-varid'>hist</span>
<a name="line-149"></a> <span class='hs-keyword'>else</span> <span class='hs-keyword'>do</span>
<a name="line-150"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-varid'>s</span><span class='hs-varop'>++</span><span class='hs-str'>" "</span><span class='hs-layout'>)</span>
<a name="line-151"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>replicate</span> <span class='hs-varid'>n1</span> <span class='hs-chr'>'\BS'</span><span class='hs-layout'>)</span>
<a name="line-152"></a> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-varid'>n</span> <span class='hs-varid'>hist</span>
<a name="line-153"></a> <span class='hs-conid'>Delete</span> <span class='hs-conid'>L</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-keyword'>let</span> <span class='hs-varid'>n1</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>n</span><span class='hs-varop'>+</span><span class='hs-num'>1</span>
<a name="line-154"></a> <span class='hs-keyword'>if</span> <span class='hs-varid'>n1</span> <span class='hs-varop'><=</span> <span class='hs-varid'>length</span> <span class='hs-varid'>s</span> <span class='hs-keyword'>then</span> <span class='hs-keyword'>do</span>
<a name="line-155"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-chr'>'\BS'</span><span class='hs-conop'>:</span><span class='hs-varid'>reverse</span> <span class='hs-layout'>(</span><span class='hs-varid'>take</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-varop'>++</span><span class='hs-str'>" "</span><span class='hs-layout'>)</span>
<a name="line-156"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>replicate</span> <span class='hs-varid'>n1</span> <span class='hs-chr'>'\BS'</span><span class='hs-layout'>)</span>
<a name="line-157"></a> <span class='hs-varid'>gl</span> <span class='hs-layout'>(</span><span class='hs-varid'>take</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span> <span class='hs-varop'>++</span> <span class='hs-varid'>drop</span> <span class='hs-varid'>n1</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-varid'>n</span> <span class='hs-varid'>hist</span>
<a name="line-158"></a> <span class='hs-keyword'>else</span> <span class='hs-keyword'>do</span>
<a name="line-159"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-varid'>s</span><span class='hs-varop'>++</span><span class='hs-str'>" "</span><span class='hs-layout'>)</span>
<a name="line-160"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>replicate</span> <span class='hs-varid'>n1</span> <span class='hs-chr'>'\BS'</span><span class='hs-layout'>)</span>
<a name="line-161"></a> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-varid'>n</span> <span class='hs-varid'>hist</span>
<a name="line-162"></a> <span class='hs-conid'>History</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>hist</span> <span class='hs-keyword'>of</span>
<a name="line-163"></a> <span class='hs-layout'>(</span><span class='hs-sel'>_fut</span><span class='hs-layout'>,</span> <span class='hs-conid'>[]</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-varid'>n</span> <span class='hs-varid'>hist</span>
<a name="line-164"></a> <span class='hs-layout'>(</span><span class='hs-varid'>fut</span><span class='hs-layout'>,</span> <span class='hs-varid'>p</span><span class='hs-conop'>:</span><span class='hs-varid'>past</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>replicate</span> <span class='hs-varid'>n</span> <span class='hs-chr'>' '</span><span class='hs-layout'>)</span>
<a name="line-165"></a> <span class='hs-varid'>delChars</span> <span class='hs-varid'>s</span>
<a name="line-166"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span>
<a name="line-167"></a> <span class='hs-varid'>gl</span> <span class='hs-varid'>p</span> <span class='hs-num'>0</span> <span class='hs-layout'>(</span><span class='hs-varid'>s</span><span class='hs-conop'>:</span><span class='hs-varid'>fut</span><span class='hs-layout'>,</span> <span class='hs-varid'>past</span><span class='hs-layout'>)</span>
<a name="line-168"></a> <span class='hs-conid'>Future</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>hist</span> <span class='hs-keyword'>of</span>
<a name="line-169"></a> <span class='hs-layout'>(</span><span class='hs-conid'>[]</span><span class='hs-layout'>,</span> <span class='hs-sel'>_past</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-varid'>n</span> <span class='hs-varid'>hist</span>
<a name="line-170"></a> <span class='hs-layout'>(</span><span class='hs-varid'>f</span><span class='hs-conop'>:</span><span class='hs-varid'>fut</span><span class='hs-layout'>,</span> <span class='hs-varid'>past</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>replicate</span> <span class='hs-varid'>n</span> <span class='hs-chr'>' '</span><span class='hs-layout'>)</span>
<a name="line-171"></a> <span class='hs-varid'>delChars</span> <span class='hs-varid'>s</span>
<a name="line-172"></a> <span class='hs-varid'>putStr</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span>
<a name="line-173"></a> <span class='hs-varid'>gl</span> <span class='hs-varid'>f</span> <span class='hs-num'>0</span> <span class='hs-layout'>(</span><span class='hs-varid'>fut</span><span class='hs-layout'>,</span> <span class='hs-varid'>s</span><span class='hs-conop'>:</span><span class='hs-varid'>past</span><span class='hs-layout'>)</span>
<a name="line-174"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>gl</span> <span class='hs-varid'>s</span> <span class='hs-varid'>n</span> <span class='hs-varid'>hist</span>
<a name="line-175"></a>
<a name="line-176"></a>
<a name="line-177"></a><a name="LineCmd"></a><span class='hs-comment'>-- Define a mini-command language, to separate the lexing of input</span>
<a name="line-178"></a><a name="LineCmd"></a><span class='hs-comment'>-- commands from their interpretation. Note there is room for expansion</span>
<a name="line-179"></a><a name="LineCmd"></a><span class='hs-comment'>-- here, e.g. commands include word-at-a-time movement, but we don't</span>
<a name="line-180"></a><a name="LineCmd"></a><span class='hs-comment'>-- currently have a key binding for that.</span>
<a name="line-181"></a><a name="LineCmd"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>LineCmd</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Char</span> <span class='hs-conid'>Char</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Move</span> <span class='hs-conid'>Cursor</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Delete</span> <span class='hs-conid'>Cursor</span>
<a name="line-182"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Accept</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Cancel</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>History</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Future</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>NoOp</span>
<a name="line-183"></a><a name="Cursor"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Cursor</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>L</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>R</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Begin</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>End</span> <span class='hs-comment'>-- not implemented yet: | WordL | WordR</span>
<a name="line-184"></a>
<a name="line-185"></a><a name="lineCmd"></a><span class='hs-comment'>-- This little lexer for keystrokes does a reasonable job, but there</span>
<a name="line-186"></a><span class='hs-comment'>-- are plenty of problems. E.g. the backspace key might generate a</span>
<a name="line-187"></a><span class='hs-comment'>-- ^H character and not display it, which results in a mismatched cursor</span>
<a name="line-188"></a><span class='hs-comment'>-- position. Behaviour is highly dependent on terminal settings I imagine.</span>
<a name="line-189"></a><span class='hs-definition'>lineCmd</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IO</span> <span class='hs-conid'>LineCmd</span>
<a name="line-190"></a><span class='hs-definition'>lineCmd</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-191"></a> <span class='hs-varid'>c1</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>hGetChar</span> <span class='hs-varid'>stdin</span>
<a name="line-192"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>c1</span> <span class='hs-keyword'>of</span>
<a name="line-193"></a> <span class='hs-chr'>'\n'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>putChar</span> <span class='hs-chr'>'\n'</span> <span class='hs-varop'>>></span> <span class='hs-varid'>return</span> <span class='hs-conid'>Accept</span>
<a name="line-194"></a> <span class='hs-chr'>'\^K'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>putChar</span> <span class='hs-chr'>'\n'</span> <span class='hs-varop'>>></span> <span class='hs-varid'>return</span> <span class='hs-conid'>Cancel</span>
<a name="line-195"></a> <span class='hs-chr'>'\DEL'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Delete</span> <span class='hs-conid'>L</span><span class='hs-layout'>)</span>
<a name="line-196"></a> <span class='hs-chr'>'\BS'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Delete</span> <span class='hs-conid'>L</span><span class='hs-layout'>)</span>
<a name="line-197"></a> <span class='hs-chr'>'\^L'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Move</span> <span class='hs-conid'>R</span><span class='hs-layout'>)</span>
<a name="line-198"></a> <span class='hs-chr'>'\^['</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-199"></a> <span class='hs-varid'>c2</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>hGetChar</span> <span class='hs-varid'>stdin</span>
<a name="line-200"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>c2</span> <span class='hs-keyword'>of</span>
<a name="line-201"></a> <span class='hs-chr'>'k'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>History</span>
<a name="line-202"></a> <span class='hs-chr'>'j'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>Future</span>
<a name="line-203"></a> <span class='hs-chr'>'['</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-204"></a> <span class='hs-varid'>c3</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>hGetChar</span> <span class='hs-varid'>stdin</span>
<a name="line-205"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>c3</span> <span class='hs-keyword'>of</span>
<a name="line-206"></a> <span class='hs-chr'>'D'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Move</span> <span class='hs-conid'>L</span><span class='hs-layout'>)</span>
<a name="line-207"></a> <span class='hs-chr'>'C'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Move</span> <span class='hs-conid'>R</span><span class='hs-layout'>)</span>
<a name="line-208"></a> <span class='hs-chr'>'A'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>History</span>
<a name="line-209"></a> <span class='hs-chr'>'B'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>Future</span>
<a name="line-210"></a> <span class='hs-chr'>'3'</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-varid'>c</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>hGetChar</span> <span class='hs-varid'>stdin</span>
<a name="line-211"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>c</span> <span class='hs-keyword'>of</span>
<a name="line-212"></a> <span class='hs-chr'>'~'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Delete</span> <span class='hs-conid'>R</span><span class='hs-layout'>)</span>
<a name="line-213"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>NoOp</span>
<a name="line-214"></a> <span class='hs-chr'>'4'</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-varid'>c</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>hGetChar</span> <span class='hs-varid'>stdin</span>
<a name="line-215"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>c</span> <span class='hs-keyword'>of</span>
<a name="line-216"></a> <span class='hs-chr'>'~'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Move</span> <span class='hs-conid'>End</span><span class='hs-layout'>)</span>
<a name="line-217"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>NoOp</span>
<a name="line-218"></a> <span class='hs-chr'>'1'</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-varid'>c</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>hGetChar</span> <span class='hs-varid'>stdin</span>
<a name="line-219"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>c</span> <span class='hs-keyword'>of</span>
<a name="line-220"></a> <span class='hs-chr'>'~'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Move</span> <span class='hs-conid'>Begin</span><span class='hs-layout'>)</span>
<a name="line-221"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>NoOp</span>
<a name="line-222"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>NoOp</span>
<a name="line-223"></a> <span class='hs-chr'>'O'</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-224"></a> <span class='hs-varid'>c3</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>hGetChar</span> <span class='hs-varid'>stdin</span>
<a name="line-225"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>c3</span> <span class='hs-keyword'>of</span>
<a name="line-226"></a> <span class='hs-chr'>'D'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Move</span> <span class='hs-conid'>L</span><span class='hs-layout'>)</span>
<a name="line-227"></a> <span class='hs-chr'>'C'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Move</span> <span class='hs-conid'>R</span><span class='hs-layout'>)</span>
<a name="line-228"></a> <span class='hs-chr'>'A'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>History</span>
<a name="line-229"></a> <span class='hs-chr'>'B'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>Future</span>
<a name="line-230"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>NoOp</span>
<a name="line-231"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>NoOp</span>
<a name="line-232"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Char</span> <span class='hs-varid'>c1</span><span class='hs-layout'>)</span>
<a name="line-233"></a>
<a name="line-234"></a><span class='hs-cpp'>#endif /* USE_READLINE */</span>
<a name="line-235"></a>
<a name="line-236"></a><span class='hs-comment'>{-
<a name="line-237"></a>-- | A simple interactive test for the line-editing functionality.
<a name="line-238"></a>
<a name="line-239"></a>-- (This illustrates the necessary use of 'initialise' and 'restore'
<a name="line-240"></a>-- as brackets around the editing loop.)
<a name="line-241"></a>testIt :: IO ()
<a name="line-242"></a>testIt = initialise >> loop >> restore
<a name="line-243"></a> where loop = do l <- getLineEdited "prompt> "
<a name="line-244"></a> when (isJust l) (putStrLn (fromJust l))
<a name="line-245"></a> when (l/=Just "quit") loop
<a name="line-246"></a>-}</span>
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