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minor refactoring of the transformer

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ESL 2023-03-21 18:02:01 -04:00
parent f8c55fd3c9
commit b64a58ed34
2 changed files with 2708 additions and 2478 deletions
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5064
k.c
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src/k.sf
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@ -259,9 +259,13 @@
(define (add-var var val env) ; adds renamed var as <core>
(extend-xenv env var (make-binding (id->sym var) (list 'ref val))))
(define (x-error msg . args)
(apply error (cons (string-append "transformer: " msg) args)))
; xform receives Scheme s-expressions and returns either Core Scheme <core>
; (always a pair) or special-form, which is either a builtin (a symbol) or
; a transformer (a procedure)
; a transformer (a procedure). Appos? flag is true when the context can
; allow xform to return a transformer; otherwise, only <core> is accepted.
(define (xform appos? sexp env)
(cond [(id? sexp)
@ -273,13 +277,13 @@
(xform appos? (hval sexp env) env)]
[else hval]))]
[(not (pair? sexp))
(xform-quote sexp env)]
(xform-quote (list sexp) env)]
[else
(let* ([head (car sexp)] [tail (cdr sexp)] [hval (xform #t head env)])
(case hval
[(syntax) (car tail)] ; internal use only
[(quote) (xform-quote (car tail) env)]
[(set!) (xform-set! (car tail) (cadr tail) env)]
[(quote) (xform-quote tail env)]
[(set!) (xform-set! tail env)]
[(set&) (xform-set& tail env)]
[(begin) (xform-begin tail env)]
[(if) (xform-if tail env)]
@ -288,46 +292,50 @@
[(letcc) (xform-letcc tail env)]
[(withcc) (xform-withcc tail env)]
[(body) (xform-body tail env)]
[(define) (xform-define (car tail) (cadr tail) env)]
[(define-syntax) (xform-define-syntax (car tail) (cadr tail) env)]
[(define) (xform-define tail env)]
[(define-syntax) (xform-define-syntax tail env)]
[else (if (integrable? hval)
(xform-integrable hval tail env)
(if (procedure? hval)
(xform appos? (hval sexp env) env)
(xform-call hval tail env)))]))]))
(define (xform-quote sexp env)
(list 'quote
(let conv ([sexp sexp])
(cond [(id? sexp) (id->sym sexp)]
[(pair? sexp) (cons (conv (car sexp)) (conv (cdr sexp)))]
[(vector? sexp) (list->vector (map conv (vector->list sexp)))]
[else sexp]))))
(define (xform-ref id env)
(let ([den (env id)])
(cond [(symbol? den) (list 'ref den)]
[else (binding-val den)])))
(define (xform-set! id exp env)
(let ([den (env id)] [xexp (xform #f exp env)])
(define (xform-quote tail env)
(if (list1? tail)
(list 'quote
(let conv ([sexp (car tail)])
(cond [(id? sexp) (id->sym sexp)]
[(pair? sexp) (cons (conv (car sexp)) (conv (cdr sexp)))]
[(vector? sexp) (list->vector (map conv (vector->list sexp)))]
[else sexp])))
(x-error "improper quote form" (cons 'quote tail))))
(define (xform-set! tail env)
(if (and (list2? tail) (id? (car tail)))
(let ([den (env (car tail))] [xexp (xform #f (cadr tail) env)])
(cond [(symbol? den) (list 'set! den xexp)]
[(binding-special? den) (binding-set-val! den xexp) '(begin)]
[else (let ([val (binding-val den)])
(if (eq? (car val) 'ref)
(list 'set! (cadr val) xexp)
(error 'transform "set! to non-identifier form")))])))
(x-error "set! to non-identifier form")))]))
(x-error "improper set! form" (cons 'set! tail))))
(define (xform-set& tail env)
(if (list1? tail)
(let ([den (env (car tail))])
(cond [(symbol? den) (list 'set& den)]
[(binding-special? den) (error 'transform "set& of a non-variable")]
[(binding-special? den) (x-error "set& of a non-variable")]
[else (let ([val (binding-val den)])
(if (eq? (car val) 'ref)
(list 'set& (cadr val))
(error 'transform "set& of a non-variable")))]))
(error 'transform "improper set& form")))
(x-error "set& of a non-variable")))]))
(x-error "improper set& form" (cons 'set& tail))))
(define (xform-begin tail env)
(if (list? tail)
@ -335,7 +343,7 @@
(if (and (pair? xexps) (null? (cdr xexps)))
(car xexps) ; (begin x) => x
(cons 'begin xexps)))
(error 'transform "improper begin form")))
(x-error "improper begin form" (cons 'begin! tail))))
(define (xform-if tail env)
(if (list? tail)
@ -343,8 +351,8 @@
(case (length xexps)
[(2) (cons 'if (append xexps '((begin))))]
[(3) (cons 'if xexps)]
[else (error 'transform "malformed if form")]))
(error 'transform "improper if form")))
[else (x-error "malformed if form" (cons 'if tail))]))
(x-error "improper if form" (cons 'if tail))))
(define (xform-call xexp tail env)
(if (list? tail)
@ -352,7 +360,7 @@
(if (and (null? xexps) (eq? (car xexp) 'lambda) (null? (cadr xexp)))
(caddr xexp) ; ((let () x)) => x
(pair* 'call xexp xexps)))
(error 'transform "improper application")))
(x-error "improper application" (cons xexp tail))))
(define (integrable-argc-match? igt n)
(case igt
@ -380,7 +388,7 @@
[ienv (add-var var nvar ienv)])
(list 'lambda (append (reverse ipars) nvar)
(xform-body (cdr tail) ienv)))]))
(error 'transform "improper lambda body" tail)))
(x-error "improper lambda body" (cons 'lambda tail))))
(define (xform-lambda* tail env)
(if (list? tail)
@ -391,22 +399,22 @@
(idslist? (car aexp))))
(list (normalize-arity (car aexp))
(xform #f (cadr aexp) env))
(error 'transform "improper lambda* clause")))
(x-error "improper lambda* clause" aexp)))
tail))
(error 'transform "improper lambda* form")))
(x-error "improper lambda* form" (cons 'lambda* tail))))
(define (xform-letcc tail env)
(if (and (list2+? tail) (id? (car tail)))
(let* ([var (car tail)] [nvar (gensym (id->sym var))])
(list 'letcc nvar
(xform-body (cdr tail) (add-var var nvar env))))
(error 'transform "improper letcc form")))
(x-error "improper letcc form" (cons 'letcc tail))))
(define (xform-withcc tail env)
(if (list2+? tail)
(list 'withcc (xform #f (car tail) env)
(xform-body (cdr tail) env))
(error 'transform "improper withcc form")))
(x-error "improper withcc form" (cons 'withcc tail))))
(define (xform-body tail env)
(if (null? tail)
@ -446,27 +454,27 @@
(map (lambda (lid) '(begin)) lids))))]
[(symbol? (car nids)) ; define
(loop (cdr ids) (cdr inits) (cdr nids)
(cons (xform-set! (car ids) (car inits) env) sets)
(cons (xform-set! (list (car ids) (car inits)) env) sets)
(cons (car nids) lids))]
[else ; define-syntax
(binding-set-val! (env (car ids)) (xform #t (car inits) env))
(loop (cdr ids) (cdr inits) (cdr nids) sets lids)])))
(define (xform-define id exp env) ; top-level only
(if (id? id)
(list 'define (id->sym id) (xform #f exp env))
(error 'transform "define of non-identifier form")))
(define (xform-define tail env) ; top-level only
(if (and (list2? tail) (id? (car tail)))
(list 'define (id->sym (car tail)) (xform #f (cadr tail) env))
(x-error "improper define form" (cons 'define tail))))
(define (xform-define-syntax id exp env) ; top-level only
(if (id? id)
(list 'define-syntax (id->sym id) (xform #t exp env))
(error 'transform "define-syntax of non-identifier form")))
(define (xform-define-syntax tail env) ; top-level only
(if (and (list2? tail) (id? (car tail)))
(list 'define-syntax (id->sym (car tail)) (xform #t (cadr tail) env))
(x-error "improper define-syntax form" (cons 'define-syntax tail))))
; ellipsis denotation is used for comparisons only
(define denotation-of-default-ellipsis
(make-binding '... (lambda (sexp env) (error '... sexp))))
(make-binding '... (lambda (sexp env) (x-error "improper use of ..." sexp))))
(define *transformers*
(list
@ -622,7 +630,7 @@
(lambda (use use-env)
(let loop ([rules rules])
(if (null? rules) (error 'transform "invalid syntax" use))
(if (null? rules) (x-error "invalid syntax" use))
(let* ([rule (car rules)] [pat (car rule)] [tmpl (cadr rule)])
(cond [(match-pattern pat use use-env) =>
(lambda (bindings) (expand-template pat tmpl bindings))]
@ -772,11 +780,13 @@
(define-syntax index-global unbox)
(define-syntax index-set-global! set-box!)
;---------------------------------------------------------------------------------------------
; String representation of S-expressions and code arguments
;---------------------------------------------------------------------------------------------
(define (c-error msg . args)
(apply error (cons (string-append "compiler: " msg) args)))
(define (write-serialized-char x port)
(cond [(or (char=? x #\%) (char=? x #\") (char=? x #\\) (char<? x #\space) (char>? x #\~))
(write-char #\% port)
@ -831,7 +841,7 @@
(write-serialized-size (string-length x) port)
(do ([i 0 (fx+ i 1)]) [(fx=? i (string-length x))]
(write-serialized-char (string-ref x i) port)))]
[else (error 'encode-sexp "cannot encode literal: ~s" x)]))
[else (c-error "cannot encode literal: ~s" x)]))
(define (write-serialized-arg arg port)
(if (and (number? arg) (exact? arg) (fx<=? 0 arg) (fx<=? arg 9))
@ -1152,7 +1162,7 @@
(write-char #\, port))
(write-string igc0 port)
(write-serialized-arg (length args) port)]
[else (error 'codegen "NYI: unsupported integrable type" igty)]))
[else (c-error "unsupported integrable type" igty)]))
(when k (write-char #\] port) (write-serialized-arg k port))]
[call (exp . args)
(cond [(and (eq? (car exp) 'lambda) (list? (cadr exp))