/usr/share/slib/r4rsyn.scm is in slib 3b1-5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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;;; Copyright (c) 1989-91 Massachusetts Institute of Technology
;;;
;;; This material was developed by the Scheme project at the
;;; Massachusetts Institute of Technology, Department of Electrical
;;; Engineering and Computer Science. Permission to copy and modify
;;; this software, to redistribute either the original software or a
;;; modified version, and to use this software for any purpose is
;;; granted, subject to the following restrictions and understandings.
;;;
;;; 1. Any copy made of this software must include this copyright
;;; notice in full.
;;;
;;; 2. Users of this software agree to make their best efforts (a) to
;;; return to the MIT Scheme project any improvements or extensions
;;; that they make, so that these may be included in future releases;
;;; and (b) to inform MIT of noteworthy uses of this software.
;;;
;;; 3. All materials developed as a consequence of the use of this
;;; software shall duly acknowledge such use, in accordance with the
;;; usual standards of acknowledging credit in academic research.
;;;
;;; 4. MIT has made no warranty or representation that the operation
;;; of this software will be error-free, and MIT is under no
;;; obligation to provide any services, by way of maintenance, update,
;;; or otherwise.
;;;
;;; 5. In conjunction with products arising from the use of this
;;; material, there shall be no use of the name of the Massachusetts
;;; Institute of Technology nor of any adaptation thereof in any
;;; advertising, promotional, or sales literature without prior
;;; written consent from MIT in each case.
;;;; R4RS Syntax
(define scheme-syntactic-environment #f)
(define (initialize-scheme-syntactic-environment!)
(set! scheme-syntactic-environment
((compose-macrologies
(make-core-primitive-macrology)
(make-binding-macrology syntactic-binding-theory
'LET-SYNTAX 'LETREC-SYNTAX 'DEFINE-SYNTAX)
(make-binding-macrology variable-binding-theory
'LET 'LETREC 'DEFINE)
(make-r4rs-primitive-macrology)
(make-core-expander-macrology)
(make-syntax-rules-macrology))
root-syntactic-environment)))
;;;; Core Primitives
(define (make-core-primitive-macrology)
(make-primitive-macrology
(lambda (define-classifier define-compiler)
(define-classifier 'BEGIN
(lambda (form environment definition-environment)
(syntax-check '(KEYWORD * FORM) form)
(make-body-item (classify/subforms (cdr form)
environment
definition-environment))))
(define-compiler 'DELAY
(lambda (form environment)
(syntax-check '(KEYWORD EXPRESSION) form)
(output/delay
(compile/subexpression (cadr form)
environment))))
(define-compiler 'IF
(lambda (form environment)
(syntax-check '(KEYWORD EXPRESSION EXPRESSION ? EXPRESSION) form)
(output/conditional
(compile/subexpression (cadr form) environment)
(compile/subexpression (caddr form) environment)
(if (null? (cdddr form))
(output/unspecific)
(compile/subexpression (cadddr form)
environment)))))
(define-compiler 'QUOTE
(lambda (form environment)
environment ;ignore
(syntax-check '(KEYWORD DATUM) form)
(output/literal-quoted (strip-syntactic-closures (cadr form))))))))
;;;; Bindings
(define (make-binding-macrology binding-theory
let-keyword letrec-keyword define-keyword)
(make-primitive-macrology
(lambda (define-classifier define-compiler)
(let ((pattern/let-like
'(KEYWORD (* (IDENTIFIER EXPRESSION)) + FORM))
(compile/let-like
(lambda (form environment body-environment output/let)
;; Force evaluation order.
(let ((bindings
(let loop
((bindings
(map (lambda (binding)
(cons (car binding)
(classify/subexpression
(cadr binding)
environment)))
(cadr form))))
(if (null? bindings)
'()
(let ((binding
(binding-theory body-environment
(caar bindings)
(cdar bindings))))
(if binding
(cons binding (loop (cdr bindings)))
(loop (cdr bindings))))))))
(output/let (map car bindings)
(map (lambda (binding)
(compile-item/expression (cdr binding)))
bindings)
(compile-item/expression
(classify/body (cddr form)
body-environment)))))))
(define-compiler let-keyword
(lambda (form environment)
(syntax-check pattern/let-like form)
(compile/let-like form
environment
(internal-syntactic-environment environment)
output/let)))
(define-compiler letrec-keyword
(lambda (form environment)
(syntax-check pattern/let-like form)
(let ((environment (internal-syntactic-environment environment)))
(reserve-names! (map car (cadr form)) environment)
(compile/let-like form
environment
environment
output/letrec)))))
(define-classifier define-keyword
(lambda (form environment definition-environment)
(syntax-check '(KEYWORD IDENTIFIER EXPRESSION) form)
(syntactic-environment/define! definition-environment
(cadr form)
(make-reserved-name-item))
(make-definition-item binding-theory
(cadr form)
(make-promise
(lambda ()
(classify/subexpression
(caddr form)
environment)))))))))
;;;; Bodies
(define (classify/body forms environment)
(let ((environment (internal-syntactic-environment environment)))
(let forms-loop
((forms forms)
(bindings '()))
(if (null? forms)
(syntax-error "no expressions in body"
"")
(let items-loop
((items
(item->list
(classify/subform (car forms)
environment
environment)))
(bindings bindings))
(cond ((null? items)
(forms-loop (cdr forms)
bindings))
((definition-item? (car items))
(items-loop (cdr items)
(let ((binding
(bind-definition-item! environment
(car items))))
(if binding
(cons binding bindings)
bindings))))
(else
(let ((body
(make-body-item
(append items
(flatten-body-items
(classify/subforms
(cdr forms)
environment
environment))))))
(make-expression-item
(lambda ()
(output/letrec
(map car bindings)
(map (lambda (binding)
(compile-item/expression (cdr binding)))
bindings)
(compile-item/expression body))) forms)))))))))
;;;; R4RS Primitives
(define (make-r4rs-primitive-macrology)
(make-primitive-macrology
(lambda (define-classifier define-compiler)
(define (transformer-keyword expander->classifier)
(lambda (form environment definition-environment)
definition-environment ;ignore
(syntax-check '(KEYWORD EXPRESSION) form)
(let ((item
(classify/subexpression (cadr form)
scheme-syntactic-environment)))
(let ((transformer (base:eval (compile-item/expression item))))
(if (procedure? transformer)
(make-keyword-item
(expander->classifier transformer environment) item)
(syntax-error "transformer not a procedure"
transformer))))))
(define-classifier 'TRANSFORMER
;; "Syntactic Closures" transformer
(transformer-keyword sc-expander->classifier))
(define-classifier 'ER-TRANSFORMER
;; "Explicit Renaming" transformer
(transformer-keyword er-expander->classifier))
(define-compiler 'LAMBDA
(lambda (form environment)
(syntax-check '(KEYWORD R4RS-BVL + FORM) form)
(let ((environment (internal-syntactic-environment environment)))
;; Force order -- bind names before classifying body.
(let ((bvl-description
(let ((rename
(lambda (identifier)
(bind-variable! environment identifier))))
(let loop ((bvl (cadr form)))
(cond ((null? bvl)
'())
((pair? bvl)
(cons (rename (car bvl)) (loop (cdr bvl))))
(else
(rename bvl)))))))
(output/lambda bvl-description
(compile-item/expression
(classify/body (cddr form)
environment)))))))
(define-compiler 'SET!
(lambda (form environment)
(syntax-check '(KEYWORD FORM EXPRESSION) form)
(output/assignment
(let loop
((form (cadr form))
(environment environment))
(cond ((identifier? form)
(let ((item
(syntactic-environment/lookup environment form)))
(if (variable-item? item)
(variable-item/name item)
(slib:error "target of assignment not a variable"
form))))
((syntactic-closure? form)
(let ((form (syntactic-closure/form form))
(environment
(filter-syntactic-environment
(syntactic-closure/free-names form)
environment
(syntactic-closure/environment form))))
(loop form
environment)))
(else
(slib:error "target of assignment not an identifier"
form))))
(compile/subexpression (caddr form)
environment))))
;; end MAKE-R4RS-PRIMITIVE-MACROLOGY
)))
;;;; Core Expanders
(define (make-core-expander-macrology)
(make-er-expander-macrology
(lambda (define-expander base-environment)
(let ((keyword (make-syntactic-closure base-environment '() 'DEFINE)))
(define-expander 'DEFINE
(lambda (form rename compare)
compare ;ignore
(if (syntax-match? '((IDENTIFIER . R4RS-BVL) + FORM) (cdr form))
`(,keyword ,(caadr form)
(,(rename 'LAMBDA) ,(cdadr form) ,@(cddr form)))
`(,keyword ,@(cdr form))))))
(let ((keyword (make-syntactic-closure base-environment '() 'LET)))
(define-expander 'LET
(lambda (form rename compare)
compare ;ignore
(if (syntax-match? '(IDENTIFIER (* (IDENTIFIER EXPRESSION)) + FORM)
(cdr form))
(let ((name (cadr form))
(bindings (caddr form)))
`((,(rename 'LETREC)
((,name (,(rename 'LAMBDA) ,(map car bindings) ,@(cdddr form))))
,name)
,@(map cadr bindings)))
`(,keyword ,@(cdr form))))))
(define-expander 'LET*
(lambda (form rename compare)
compare ;ignore
(if (syntax-match? '((* (IDENTIFIER EXPRESSION)) + FORM) (cdr form))
(let ((bindings (cadr form))
(body (cddr form))
(keyword (rename 'LET)))
(if (null? bindings)
`(,keyword ,bindings ,@body)
(let loop ((bindings bindings))
(if (null? (cdr bindings))
`(,keyword ,bindings ,@body)
`(,keyword (,(car bindings))
,(loop (cdr bindings)))))))
(ill-formed-syntax form))))
(define-expander 'AND
(lambda (form rename compare)
compare ;ignore
(if (syntax-match? '(* EXPRESSION) (cdr form))
(let ((operands (cdr form)))
(if (null? operands)
`#T
(let ((if-keyword (rename 'IF)))
(let loop ((operands operands))
(if (null? (cdr operands))
(car operands)
`(,if-keyword ,(car operands)
,(loop (cdr operands))
#F))))))
(ill-formed-syntax form))))
(define-expander 'OR
(lambda (form rename compare)
compare ;ignore
(if (syntax-match? '(* EXPRESSION) (cdr form))
(let ((operands (cdr form)))
(if (null? operands)
`#F
(let ((let-keyword (rename 'LET))
(if-keyword (rename 'IF))
(temp (rename 'TEMP)))
(let loop ((operands operands))
(if (null? (cdr operands))
(car operands)
`(,let-keyword ((,temp ,(car operands)))
(,if-keyword ,temp
,temp
,(loop (cdr operands)))))))))
(ill-formed-syntax form))))
(define-expander 'CASE
(lambda (form rename compare)
(if (syntax-match? '(EXPRESSION + (DATUM + EXPRESSION)) (cdr form))
(letrec
((process-clause
(lambda (clause rest)
(cond ((null? (car clause))
(process-rest rest))
((and (identifier? (car clause))
(compare (rename 'ELSE) (car clause))
(null? rest))
`(,(rename 'BEGIN) ,@(cdr clause)))
((list? (car clause))
`(,(rename 'IF) (,(rename 'MEMV) ,(rename 'TEMP)
',(car clause))
(,(rename 'BEGIN) ,@(cdr clause))
,(process-rest rest)))
(else
(syntax-error "ill-formed clause" clause)))))
(process-rest
(lambda (rest)
(if (null? rest)
(unspecific-expression)
(process-clause (car rest) (cdr rest))))))
`(,(rename 'LET) ((,(rename 'TEMP) ,(cadr form)))
,(process-clause (caddr form) (cdddr form))))
(ill-formed-syntax form))))
(define-expander 'COND
(lambda (form rename compare)
(letrec
((process-clause
(lambda (clause rest)
(cond
((or (not (list? clause))
(null? clause))
(syntax-error "ill-formed clause" clause))
((and (identifier? (car clause))
(compare (rename 'ELSE) (car clause)))
(cond
((or (null? (cdr clause))
(and (identifier? (cadr clause))
(compare (rename '=>) (cadr clause))))
(syntax-error "ill-formed ELSE clause" clause))
((not (null? rest))
(syntax-error "misplaced ELSE clause" clause))
(else
`(,(rename 'BEGIN) ,@(cdr clause)))))
((null? (cdr clause))
`(,(rename 'OR) ,(car clause) ,(process-rest rest)))
((and (identifier? (cadr clause))
(compare (rename '=>) (cadr clause)))
(if (and (pair? (cddr clause))
(null? (cdddr clause)))
`(,(rename 'LET)
((,(rename 'TEMP) ,(car clause)))
(,(rename 'IF) ,(rename 'TEMP)
(,(caddr clause) ,(rename 'TEMP))
,(process-rest rest)))
(syntax-error "ill-formed => clause" clause)))
(else
`(,(rename 'IF) ,(car clause)
(,(rename 'BEGIN) ,@(cdr clause))
,(process-rest rest))))))
(process-rest
(lambda (rest)
(if (null? rest)
(unspecific-expression)
(process-clause (car rest) (cdr rest))))))
(let ((clauses (cdr form)))
(if (null? clauses)
(syntax-error "no clauses" form)
(process-clause (car clauses) (cdr clauses)))))))
(define-expander 'DO
(lambda (form rename compare)
compare ;ignore
(if (syntax-match? '((* (IDENTIFIER EXPRESSION ? EXPRESSION))
(+ EXPRESSION)
* FORM)
(cdr form))
(let ((bindings (cadr form)))
`(,(rename 'LETREC)
((,(rename 'DO-LOOP)
(,(rename 'LAMBDA)
,(map car bindings)
(,(rename 'IF) ,(caaddr form)
,(if (null? (cdaddr form))
(unspecific-expression)
`(,(rename 'BEGIN) ,@(cdaddr form)))
(,(rename 'BEGIN)
,@(cdddr form)
(,(rename 'DO-LOOP)
,@(map (lambda (binding)
(if (null? (cddr binding))
(car binding)
(caddr binding)))
bindings)))))))
(,(rename 'DO-LOOP) ,@(map cadr bindings))))
(ill-formed-syntax form))))
(define-expander 'QUASIQUOTE
(lambda (form rename compare)
(define (descend-quasiquote x level return)
(cond ((pair? x) (descend-quasiquote-pair x level return))
((vector? x) (descend-quasiquote-vector x level return))
(else (return 'QUOTE x))))
(define (descend-quasiquote-pair x level return)
(cond ((not (and (pair? x)
(identifier? (car x))
(pair? (cdr x))
(null? (cddr x))))
(descend-quasiquote-pair* x level return))
((compare (rename 'QUASIQUOTE) (car x))
(descend-quasiquote-pair* x (+ level 1) return))
((compare (rename 'UNQUOTE) (car x))
(if (zero? level)
(return 'UNQUOTE (cadr x))
(descend-quasiquote-pair* x (- level 1) return)))
((compare (rename 'UNQUOTE-SPLICING) (car x))
(if (zero? level)
(return 'UNQUOTE-SPLICING (cadr x))
(descend-quasiquote-pair* x (- level 1) return)))
(else
(descend-quasiquote-pair* x level return))))
(define (descend-quasiquote-pair* x level return)
(descend-quasiquote
(car x) level
(lambda (car-mode car-arg)
(descend-quasiquote
(cdr x) level
(lambda (cdr-mode cdr-arg)
(cond ((and (eq? car-mode 'QUOTE) (eq? cdr-mode 'QUOTE))
(return 'QUOTE x))
((eq? car-mode 'UNQUOTE-SPLICING)
(if (and (eq? cdr-mode 'QUOTE) (null? cdr-arg))
(return 'UNQUOTE car-arg)
(return 'APPEND
(list car-arg
(finalize-quasiquote cdr-mode
cdr-arg)))))
((and (eq? cdr-mode 'QUOTE) (list? cdr-arg))
(return 'LIST
(cons (finalize-quasiquote car-mode car-arg)
(map (lambda (element)
(finalize-quasiquote 'QUOTE
element))
cdr-arg))))
((eq? cdr-mode 'LIST)
(return 'LIST
(cons (finalize-quasiquote car-mode car-arg)
cdr-arg)))
(else
(return
'CONS
(list (finalize-quasiquote car-mode car-arg)
(finalize-quasiquote cdr-mode cdr-arg))))))))))
(define (descend-quasiquote-vector x level return)
(descend-quasiquote
(vector->list x) level
(lambda (mode arg)
(case mode
((QUOTE) (return 'QUOTE x))
((LIST) (return 'VECTOR arg))
(else
(return 'LIST->VECTOR
(list (finalize-quasiquote mode arg))))))))
(define (finalize-quasiquote mode arg)
(case mode
((QUOTE) `(,(rename 'QUOTE) ,arg))
((UNQUOTE) arg)
((UNQUOTE-SPLICING) (syntax-error ",@ in illegal context" arg))
(else `(,(rename mode) ,@arg))))
(if (syntax-match? '(EXPRESSION) (cdr form))
(descend-quasiquote (cadr form) 0 finalize-quasiquote)
(ill-formed-syntax form))))
;;; end MAKE-CORE-EXPANDER-MACROLOGY
)))
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