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chicken-syntax.scm
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;;;; chicken-syntax.scm - non-standard syntax extensions
;
; Copyright (c) 2008-2015, The CHICKEN Team
; Copyright (c) 2000-2007, Felix L. Winkelmann
; All rights reserved.
;
; Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
; conditions are met:
;
; Redistributions of source code must retain the above copyright notice, this list of conditions and the following
; disclaimer.
; Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
; disclaimer in the documentation and/or other materials provided with the distribution.
; Neither the name of the author nor the names of its contributors may be used to endorse or promote
; products derived from this software without specific prior written permission.
;
; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS
; OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
; AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
; CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
; CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
; SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
; THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
; OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
; POSSIBILITY OF SUCH DAMAGE.
(declare
(unit chicken-syntax)
(disable-interrupts)
(fixnum) )
#+(not debugbuild)
(declare
(no-bound-checks)
(no-procedure-checks))
(##sys#provide 'chicken-syntax)
;;; Non-standard macros:
(define ##sys#chicken-macro-environment
(let ((me0 (##sys#macro-environment)))
(##sys#extend-macro-environment
'define-constant
'()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'define-constant form '(_ symbol _))
`(##core#define-constant ,@(cdr form)))))
(##sys#extend-macro-environment
'define-record '()
(##sys#er-transformer
(lambda (x r c)
(##sys#check-syntax 'define-record x '(_ symbol . _))
(let* ((name (cadr x))
(slots (cddr x))
(prefix (symbol->string name))
(%define (r 'define))
(%setter (r 'setter))
(%getter-with-setter (r 'getter-with-setter))
(slotnames
(map (lambda (slot)
(cond ((symbol? slot) slot)
((and (pair? slot)
(c (car slot) %setter)
(pair? (cdr slot))
(symbol? (cadr slot))
(null? (cddr slot)))
(cadr slot))
(else
(syntax-error
'define-record "invalid slot specification" slot))))
slots)))
`(##core#begin
(,%define
,(string->symbol (string-append "make-" prefix))
(##core#lambda
,slotnames
(##sys#make-structure (##core#quote ,name) ,@slotnames)))
(,%define
,(string->symbol (string-append prefix "?"))
(##core#lambda (x) (##sys#structure? x ',name)) )
,@(let mapslots ((slots slots) (i 1))
(if (eq? slots '())
slots
(let* ((a (car slots))
(has-setter (not (symbol? a)))
(slotname (symbol->string (if has-setter (cadr a) a)))
(setr (string->symbol (string-append prefix "-" slotname "-set!")))
(getr (string->symbol (string-append prefix "-" slotname)))
(setrcode
`(##core#lambda
(x val)
(##core#check (##sys#check-structure x (##core#quote ,name)))
(##sys#block-set! x ,i val) ) ))
(cons
`(##core#begin
,@(if has-setter
'()
`((,%define ,setr ,setrcode)))
(,%define
,getr
,(if has-setter
`(,%getter-with-setter
(##core#lambda
(x)
(##core#check (##sys#check-structure x (##core#quote ,name)))
(##sys#block-ref x ,i) )
,setrcode)
`(##core#lambda
(x)
(##core#check (##sys#check-structure x (##core#quote ,name)))
(##sys#block-ref x ,i) ) ) ) )
(mapslots (##sys#slot slots 1) (fx+ i 1)) ) ) ) ) ) ) ) ) )
(##sys#extend-macro-environment
'receive
'()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'receive form '(_ _ . #(_ 0)))
(cond ((null? (cddr form))
`(##sys#call-with-values (##core#lambda () ,@(cdr form)) ##sys#list) )
(else
(##sys#check-syntax 'receive form '(_ lambda-list _ . #(_ 1)))
(let ((vars (cadr form))
(exp (caddr form))
(rest (cdddr form)))
(if (and (pair? vars) (null? (cdr vars)))
`(##core#let ((,(car vars) ,exp)) ,@rest)
`(##sys#call-with-values
(##core#lambda () ,exp)
(##core#lambda ,vars ,@rest)) ) ) ) ) )))
(##sys#extend-macro-environment
'time '()
(##sys#er-transformer
(lambda (form r c)
(let ((rvar (r 't)))
`(##core#begin
(##sys#start-timer)
(##sys#call-with-values
(##core#lambda () ,@(cdr form))
(##core#lambda
,rvar
(##sys#display-times (##sys#stop-timer))
(##sys#apply ##sys#values ,rvar) ) ) ) ) ) ) )
(##sys#extend-macro-environment
'declare '()
(##sys#er-transformer
(lambda (form r c)
`(##core#declare ,@(cdr form)))))
(##sys#extend-macro-environment
'include '()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'include form '(_ string))
`(##core#include ,(cadr form)))))
(##sys#extend-macro-environment
'assert '()
(##sys#er-transformer
(let ((string-append string-append))
(lambda (form r c)
(##sys#check-syntax 'assert form '#(_ 1))
(let* ((exp (cadr form))
(msg-and-args (cddr form))
(msg (optional msg-and-args "assertion failed"))
(tmp (r 'tmp)))
(when (string? msg)
(and-let* ((ln (get-line-number form)))
(set! msg (string-append "(" ln ") " msg))))
`(##core#let ((,tmp ,exp))
(##core#if (##core#check ,tmp)
,tmp
(##sys#error
,msg
,@(if (pair? msg-and-args)
(cdr msg-and-args)
`((##core#quote ,(##sys#strip-syntax exp))))))))))))
(##sys#extend-macro-environment
'ensure
'()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'ensure form '#(_ 3))
(let ((pred (cadr form))
(exp (caddr form))
(args (cdddr form))
(tmp (r 'tmp)))
`(##core#let
([,tmp ,exp])
(##core#if (##core#check (,pred ,tmp))
,tmp
(##sys#signal-hook
#:type-error
,@(if (pair? args)
args
`((##core#immutable (##core#quote "argument has incorrect type"))
,tmp (##core#quote ,pred)) ) ) ) ) ) ) ) )
(##sys#extend-macro-environment
'fluid-let '()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'fluid-let form '(_ #((symbol _) 0) . _))
(let* ((clauses (cadr form))
(body (cddr form))
(ids (##sys#map car clauses))
(new-tmps (##sys#map (lambda (x) (r (gensym))) clauses))
(old-tmps (##sys#map (lambda (x) (r (gensym))) clauses)))
`(##core#let
(,@(map ##sys#list new-tmps (##sys#map cadr clauses))
,@(map ##sys#list old-tmps
(let loop ((n (length clauses)))
(if (eq? n 0)
'()
(cons #f (loop (fx- n 1))) ) ) ) )
(##sys#dynamic-wind
(##core#lambda ()
,@(map (lambda (ot id) `(##core#set! ,ot ,id))
old-tmps ids)
,@(map (lambda (id nt) `(##core#set! ,id ,nt))
ids new-tmps)
(##core#undefined) )
(##core#lambda () ,@body)
(##core#lambda ()
,@(map (lambda (nt id) `(##core#set! ,nt ,id))
new-tmps ids)
,@(map (lambda (id ot) `(##core#set! ,id ,ot))
ids old-tmps)
(##core#undefined) ) ) ) ) )))
(##sys#extend-macro-environment
'eval-when '()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'eval-when form '#(_ 2))
(let* ((situations (cadr form))
(body `(##core#begin ,@(cddr form)))
(%eval (r 'eval))
(%compile (r 'compile))
(%load (r 'load))
(e #f)
(co #f)
(l #f))
(let loop ([ss situations])
(if (pair? ss)
(let ((s (car ss)))
(cond ((c s %eval) (set! e #t))
((c s %load) (set! l #t))
((c s %compile) (set! co #t))
(else (##sys#error "invalid situation specifier" (car ss)) ))
(loop (##sys#slot ss 1)) ) ) )
(if (memq '#:compiling ##sys#features)
(cond [(and co l) `(##core#compiletimetoo ,body)]
[co `(##core#compiletimeonly ,body)]
[l body]
[else '(##core#undefined)] )
(if e
body
'(##core#undefined) ) ) ) ) ) )
(##sys#extend-macro-environment
'parameterize '()
(##sys#er-transformer
(lambda (form r c)
(define (pname p)
(if (symbol? p)
(gensym p)
(gensym "parameter")))
(##sys#check-syntax 'parameterize form '#(_ 2))
(let* ((bindings (cadr form))
(body (cddr form))
(swap (r 'swap))
(mode (r 'mode))
(params (##sys#map car bindings))
(vals (##sys#map cadr bindings))
(aliases (##sys#map (lambda (z) (r (pname z))) params))
(aliases2 (##sys#map (lambda (z) (r (gensym))) params)) )
`(##core#let
,(map ##sys#list aliases params)
(##core#let
,(map ##sys#list aliases2 vals)
(##core#let
((,mode #f))
(##core#let
((,swap (##core#lambda
()
,@(map (lambda (a a2)
`(##core#let ((t (,a))) (,a ,a2 ,mode)
(##core#set! ,a2 t)))
aliases aliases2)
(##core#set! ,mode #t))))
(##sys#dynamic-wind
,swap
(##core#lambda () ,@body)
,swap) ) ) ) )))))
(##sys#extend-macro-environment
'when '()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'when form '#(_ 2))
`(##core#if ,(cadr form)
(##core#begin ,@(cddr form))))))
(##sys#extend-macro-environment
'unless '()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'unless form '#(_ 2))
`(##core#if ,(cadr form)
(##core#undefined)
(##core#begin ,@(cddr form))))))
(##sys#extend-macro-environment
'set!-values '()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'set!-values form '(_ lambda-list _))
(##sys#expand-multiple-values-assignment (cadr form) (caddr form)))))
(set! ##sys#define-values-definition
(##sys#extend-macro-environment
'define-values '()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'define-values form '(_ lambda-list _))
(##sys#decompose-lambda-list
(cadr form)
(lambda (vars argc rest)
(for-each (lambda (nm)
(let ((name (##sys#get nm '##core#macro-alias nm)))
(##sys#register-export name (##sys#current-module))))
vars)))
`(,(r 'set!-values) ,@(cdr form))))))
(##sys#extend-macro-environment
'let-values '()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'let-values form '(_ list . _))
(let ((vbindings (cadr form))
(body (cddr form)))
(letrec ((append* (lambda (il l)
(if (not (pair? il))
(cons il l)
(cons (car il)
(append* (cdr il) l)))))
(map* (lambda (proc l)
(cond ((null? l) '())
((not (pair? l)) (proc l))
(else (cons (proc (car l)) (map* proc (cdr l))))))))
(let* ([llists (map car vbindings)]
[vars (let loop ((llists llists) (acc '()))
(if (null? llists)
acc
(let* ((llist (car llists))
(new-acc
(cond ((list? llist) (append llist acc))
((pair? llist) (append* llist acc))
(else (cons llist acc)))))
(loop (cdr llists) new-acc))))]
[aliases (map (lambda (v) (cons v (r (gensym v)))) vars)]
[lookup (lambda (v) (cdr (assq v aliases)))]
[llists2 (let loop ((llists llists) (acc '()))
(if (null? llists)
(reverse acc)
(let* ((llist (car llists))
(new-acc
(cond ((not (pair? llist)) (cons (lookup llist) acc))
(else (cons (map* lookup llist) acc)))))
(loop (cdr llists) new-acc))))])
(let fold ([llists llists]
[exps (map (lambda (x) (cadr x)) vbindings)]
[llists2 llists2] )
(cond ((null? llists)
`(##core#let
,(map (lambda (v) (##sys#list v (lookup v))) vars)
,@body) )
((and (pair? (car llists2)) (null? (cdar llists2)))
`(##core#let
((,(caar llists2) ,(car exps)))
,(fold (cdr llists) (cdr exps) (cdr llists2)) ) )
(else
`(##sys#call-with-values
(##core#lambda () ,(car exps))
(##core#lambda
,(car llists2)
,(fold (cdr llists) (cdr exps) (cdr llists2))) ) ) ) ) ) ) ) ) ) )
(##sys#extend-macro-environment
'let*-values '()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'let*-values form '(_ list . _))
(let ((vbindings (cadr form))
(body (cddr form))
(%let-values (r 'let-values)) )
(let fold ([vbindings vbindings])
(if (null? vbindings)
`(##core#let () ,@body)
`(,%let-values (,(car vbindings))
,(fold (cdr vbindings))) ) ) ))))
;;XXX do we need letrec*-values ?
(##sys#extend-macro-environment
'letrec-values '()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'letrec-values form '(_ #((lambda-list . _) 0) . _))
(let ((vbindings (cadr form))
(body (cddr form)))
(let ((vars (map car vbindings))
(exprs (map cadr vbindings)))
`(##core#let
,(map (lambda (v) (##sys#list v '(##core#undefined)))
(foldl (lambda (l v) ; flatten multi-value formals
(##sys#append l (##sys#decompose-lambda-list
v (lambda (a _ _) a))))
'()
vars))
,@(map ##sys#expand-multiple-values-assignment vars exprs)
,@body))))))
(##sys#extend-macro-environment
'nth-value
`((list-ref . ,(##sys#primitive-alias 'list-ref)))
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'nth-value form '(_ _ _))
(let ((v (r 'tmp)))
`(##sys#call-with-values
(##core#lambda () ,(caddr form))
(##core#lambda ,v (,(r 'list-ref) ,v ,(cadr form))))))))
(##sys#extend-macro-environment
'define-inline '()
(##sys#er-transformer
(lambda (form r c)
(letrec ([quotify-proc
(lambda (xs id)
(##sys#check-syntax id xs '#(_ 1))
(let* ([head (car xs)]
[name (if (pair? head) (car head) head)]
[val (if (pair? head)
`(##core#lambda ,(cdr head) ,@(cdr xs))
(cadr xs) ) ] )
(when (or (not (pair? val))
(and (not (eq? '##core#lambda (car val)))
(not (c (r 'lambda) (car val)))))
(syntax-error
'define-inline "invalid substitution form - must be lambda"
name val) )
(list name val) ) ) ] )
`(##core#define-inline ,@(quotify-proc (cdr form) 'define-inline)))) ) )
(##sys#extend-macro-environment
'and-let* '()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'and-let* form '(_ #(_ 0) . _))
(let ((bindings (cadr form))
(body (cddr form)))
(let fold ([bs bindings])
(if (null? bs)
`(##core#begin ,@body)
(let ([b (car bs)]
[bs2 (cdr bs)] )
(cond [(not (pair? b)) `(##core#if ,b ,(fold bs2) #f)]
[(null? (cdr b)) `(##core#if ,(car b) ,(fold bs2) #f)]
[else
(##sys#check-syntax 'and-let* b '(symbol _))
(let ((var (car b)))
`(##core#let ((,var ,(cadr b)))
(##core#if ,var ,(fold bs2) #f) ) ) ] ) ) ) ) ) ) ) )
(##sys#extend-macro-environment
'select '()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'select form '(_ _ . _))
(let ((exp (cadr form))
(body (cddr form))
(tmp (r 'tmp))
(%else (r 'else))
(%or (r 'or)))
`(##core#let
((,tmp ,exp))
,(let expand ((clauses body) (else? #f))
(cond ((null? clauses)
'(##core#undefined) )
((not (pair? clauses))
(syntax-error 'select "invalid syntax" clauses))
(else
(let ((clause (##sys#slot clauses 0))
(rclauses (##sys#slot clauses 1)) )
(##sys#check-syntax 'select clause '#(_ 1))
(cond ((c %else (car clause))
(expand rclauses #t)
`(##core#begin ,@(cdr clause)) )
(else?
(##sys#notice
"non-`else' clause following `else' clause in `select'"
(##sys#strip-syntax clause))
(expand rclauses #t)
'(##core#begin))
(else
`(##core#if
(,%or ,@(map (lambda (x) `(##sys#eqv? ,tmp ,x))
(car clause) ) )
(##core#begin ,@(cdr clause))
,(expand rclauses #f) ) ) ) ) ) ) ) ) ) ) ) )
;;; Optional argument handling:
;;; Copyright (C) 1996 by Olin Shivers.
;;;
;;; This file defines three macros for parsing optional arguments to procs:
;;; (LET-OPTIONALS arg-list ((var1 default1) ...) . body)
;;; (LET-OPTIONALS* arg-list ((var1 default1) ...) . body)
;;; (:OPTIONAL rest-arg default-exp)
;;;
;;; The LET-OPTIONALS macro is defined using the Clinger/Rees
;;; explicit-renaming low-level macro system. You'll have to do some work to
;;; port it to another macro system.
;;;
;;; The LET-OPTIONALS* and :OPTIONAL macros are defined with simple
;;; high-level macros, and should be portable to any R4RS system.
;;;
;;; These macros are all careful to evaluate their default forms *only* if
;;; their values are needed.
;;;
;;; The only non-R4RS dependencies in the macros are ERROR
;;; and CALL-WITH-VALUES.
;;; -Olin
;;; (LET-OPTIONALS arg-list ((var1 default1) ...)
;;; body
;;; ...)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; This form is for binding a procedure's optional arguments to either
;;; the passed-in values or a default.
;;;
;;; The expression takes a rest list ARG-LIST and binds the VARi to
;;; the elements of the rest list. When there are no more elements, then
;;; the remaining VARi are bound to their corresponding DEFAULTi values.
;;;
;;; - The default expressions are *not* evaluated unless needed.
;;;
;;; - When evaluated, the default expressions are carried out in the *outer*
;;; environment. That is, the DEFAULTi forms do *not* see any of the VARi
;;; bindings.
;;;
;;; I originally wanted to have the DEFAULTi forms get eval'd in a LET*
;;; style scope -- DEFAULT3 would see VAR1 and VAR2, etc. But this is
;;; impossible to implement without side effects or redundant conditional
;;; tests. If I drop this requirement, I can use the efficient expansion
;;; shown below. If you need LET* scope, use the less-efficient
;;; LET-OPTIONALS* form defined below.
;;;
;;; Example:
;;; (define (read-string! str . maybe-args)
;;; (let-optionals maybe-args ((port (current-input-port))
;;; (start 0)
;;; (end (string-length str)))
;;; ...))
;;;
;;; expands to:
;;;
;;; (let* ((body (lambda (port start end) ...))
;;; (end-def (lambda (%port %start) (body %port %start <end-default>)))
;;; (start-def (lambda (%port) (end-def %port <start-default>)))
;;; (port-def (lambda () (start-def <port-def>))))
;;; (if (null? rest) (port-def)
;;; (let ((%port (car rest))
;;; (rest (cdr rest)))
;;; (if (null? rest) (start-def %port)
;;; (let ((%start (car rest))
;;; (rest (cdr rest)))
;;; (if (null? rest) (end-def %port %start)
;;; (let ((%end (car rest))
;;; (rest (cdr rest)))
;;; (if (null? rest) (body %port %start %end)
;;; (error ...)))))))))
;;; (LET-OPTIONALS args ((var1 default1) ...) body1 ...)
(##sys#extend-macro-environment
'let-optionals
`((car . ,(##sys#primitive-alias 'car))
(cdr . ,(##sys#primitive-alias 'cdr)))
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'let-optionals form '(_ _ . _))
(let ((arg-list (cadr form))
(var/defs (caddr form))
(body (cdddr form)))
;; This guy makes the END-DEF, START-DEF, PORT-DEF definitions above.
;; I wish I had a reasonable loop macro.
(define (make-default-procs vars body-proc defaulter-names defs rename)
(let recur ((vars (reverse vars))
(defaulter-names (reverse defaulter-names))
(defs (reverse defs))
(next-guy body-proc))
(if (null? vars) '()
(let ((vars (cdr vars)))
`((,(car defaulter-names)
(##core#lambda ,(reverse vars)
(,next-guy ,@(reverse vars) ,(car defs))))
. ,(recur vars
(cdr defaulter-names)
(cdr defs)
(car defaulter-names)))))))
;; This guy makes the (IF (NULL? REST) (PORT-DEF) ...) tree above.
(define (make-if-tree vars defaulters body-proc rest rename)
(let recur ((vars vars) (defaulters defaulters) (non-defaults '()))
(if (null? vars)
`(,body-proc . ,(reverse non-defaults))
(let ((v (car vars)))
`(##core#if (null? ,rest)
(,(car defaulters) . ,(reverse non-defaults))
(##core#let ((,v (,(r 'car) ,rest)) ; we use car/cdr, because of rest-list optimization
(,rest (,(r 'cdr) ,rest)))
,(recur (cdr vars)
(cdr defaulters)
(cons v non-defaults))))))))
(##sys#check-syntax 'let-optionals var/defs '#((variable _) 0))
(##sys#check-syntax 'let-optionals body '#(_ 1))
(let* ((vars (map car var/defs))
(prefix-sym (lambda (prefix sym)
(string->symbol (string-append prefix (symbol->string sym)))))
;; Private vars, one for each user var.
;; We prefix the % to help keep macro-expanded code from being
;; too confusing.
(vars2 (map (lambda (v) (r (prefix-sym "%" v)))
vars))
(defs (map cadr var/defs))
(body-proc (r 'body))
;; A private var, bound to the value of the ARG-LIST expression.
(rest-var (r '_%rest))
(defaulter-names (map (lambda (var) (r (prefix-sym "def-" var)))
vars))
(defaulters (make-default-procs vars2 body-proc
defaulter-names defs gensym))
(if-tree (make-if-tree vars2 defaulter-names body-proc
rest-var gensym)))
`(,(r 'let*) ((,rest-var ,arg-list)
(,body-proc (##core#lambda ,vars . ,body))
. ,defaulters)
,if-tree) ) ))))
;;; (optional rest-arg default-exp)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; This form is for evaluating optional arguments and their defaults
;;; in simple procedures that take a *single* optional argument. It is
;;; a macro so that the default will not be computed unless it is needed.
;;;
;;; REST-ARG is a rest list from a lambda -- e.g., R in
;;; (lambda (a b . r) ...)
;;; - If REST-ARG has 0 elements, evaluate DEFAULT-EXP and return that.
;;; - If REST-ARG has 1 element, return that element.
(##sys#extend-macro-environment
'optional
`((null? . ,(##sys#primitive-alias 'null?))
(car . ,(##sys#primitive-alias 'car))
(cdr . ,(##sys#primitive-alias 'cdr)) )
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'optional form '(_ _ . #(_ 0 1)))
(let ((var (r 'tmp)))
`(##core#let ((,var ,(cadr form)))
(##core#if (,(r 'null?) ,var)
,(optional (cddr form) #f)
(,(r 'car) ,var)))))))
;;; (LET-OPTIONALS* args ((var1 default1) ... [rest]) body1 ...)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; This is just like LET-OPTIONALS, except that the DEFAULTi forms
;;; are evaluated in a LET*-style environment. That is, DEFAULT3 is evaluated
;;; within the scope of VAR1 and VAR2, and so forth.
;;;
;;; - If the last form in the ((var1 default1) ...) list is not a
;;; (VARi DEFAULTi) pair, but a simple variable REST, then it is
;;; bound to any left-over values. For example, if we have VAR1 through
;;; VAR7, and ARGS has 9 values, then REST will be bound to the list of
;;; the two values of ARGS. If ARGS is too short, causing defaults to
;;; be used, then REST is bound to '().
(##sys#extend-macro-environment
'let-optionals*
`((null? . ,(##sys#primitive-alias 'null?)))
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'let-optionals* form '(_ _ list . _))
(let ((args (cadr form))
(var/defs (caddr form))
(body (cdddr form))
(%null? (r 'null?))
(%car (r 'car))
(%cdr (r 'cdr)))
(let ((rvar (r 'tmp)))
`(##core#let
((,rvar ,args))
,(let loop ([args rvar] [vardefs var/defs])
(if (null? vardefs)
`(##core#let () ,@body)
(let ([head (car vardefs)])
(if (pair? head)
(let ((rvar2 (r 'tmp2)))
`(##core#let ((,(car head) (##core#if (,%null? ,args)
,(cadr head)
(,%car ,args)))
(,rvar2 (##core#if (,%null? ,args)
'()
(,%cdr ,args))) )
,(loop rvar2 (cdr vardefs)) ) )
`(##core#let ((,head ,args)) ,@body) ) ) ) ) ) ) ))))
;;; case-lambda (SRFI-16):
(##sys#extend-macro-environment
'case-lambda
`((>= . ,(##sys#primitive-alias '>=))
(car . ,(##sys#primitive-alias 'car))
(cdr . ,(##sys#primitive-alias 'cdr))
(eq? . ,(##sys#primitive-alias 'eq?))
(length . ,(##sys#primitive-alias 'length)))
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'case-lambda form '(_ . _))
(define (genvars n)
(let loop ([i 0])
(if (fx>= i n)
'()
(cons (r (gensym)) (loop (fx+ i 1))) ) ) )
(require 'srfi-1) ; ugh...
(let* ((mincount (apply min (map (lambda (c)
(##sys#decompose-lambda-list
(car c)
(lambda (vars argc rest) argc) ) )
(cdr form))))
(minvars (genvars mincount))
(rvar (r 'rvar))
(lvar (r 'lvar))
(%>= (r '>=))
(%eq? (r 'eq?))
(%car (r 'car))
(%cdr (r 'cdr))
(%length (r 'length)))
`(##core#lambda
,(append minvars rvar)
(##core#let
((,lvar (,%length ,rvar)))
,(fold-right
(lambda (c body)
(##sys#decompose-lambda-list
(car c)
(lambda (vars argc rest)
(##sys#check-syntax 'case-lambda (car c) 'lambda-list)
`(##core#if ,(let ([a2 (fx- argc mincount)])
(if rest
(if (zero? a2)
#t
`(,%>= ,lvar ,a2) )
`(,%eq? ,lvar ,a2) ) )
,(receive (vars1 vars2)
(split-at! (take vars argc) mincount)
(let ((bindings
(let build ((vars2 vars2) (vrest rvar))
(if (null? vars2)
(cond (rest `(##core#let ((,rest ,vrest)) ,@(cdr c)))
((null? (cddr c)) (cadr c))
(else `(##core#let () ,@(cdr c))) )
(let ((vrest2 (r (gensym))))
`(##core#let ((,(car vars2) (,%car ,vrest))
(,vrest2 (,%cdr ,vrest)) )
,(if (pair? (cdr vars2))
(build (cdr vars2) vrest2)
(build '() vrest2) ) ) ) ) ) ) )
(if (null? vars1)
bindings
`(##core#let ,(map list vars1 minvars) ,bindings) ) ) )
,body) ) ) )
'(##core#check (##sys#error (##core#immutable (##core#quote "no matching clause in call to 'case-lambda' form"))))
(cdr form))))))))
;;; Record printing:
(##sys#extend-macro-environment
'define-record-printer '()
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'define-record-printer form '(_ _ . _))
(let ([head (cadr form)]
[body (cddr form)])
(cond [(pair? head)
(##sys#check-syntax
'define-record-printer (cons head body)
'((symbol symbol symbol) . #(_ 1)))
`(##sys#register-record-printer
',(##sys#slot head 0)
(##core#lambda ,(##sys#slot head 1) ,@body)) ]
[else
(##sys#check-syntax 'define-record-printer (cons head body) '(symbol _))
`(##sys#register-record-printer ',head ,@body) ] ) ))))
;;; Exceptions:
(##sys#extend-macro-environment
'handle-exceptions
`((call-with-current-continuation . ,(##sys#primitive-alias 'call-with-current-continuation))
(with-exception-handler . ,(##sys#primitive-alias 'with-exception-handler)))
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'handle-exceptions form '(_ variable _ . _))
(let ((k (r 'k))
(args (r 'args)))
`((,(r 'call-with-current-continuation)
(##core#lambda
(,k)
(,(r 'with-exception-handler)
(##core#lambda (,(cadr form)) (,k (##core#lambda () ,(caddr form))))
(##core#lambda
()
(##sys#call-with-values
(##core#lambda () ,@(cdddr form))
(##core#lambda
,args
(,k (##core#lambda () (##sys#apply ##sys#values ,args)))) ) ) ) ) ) ) ) ) ) )
(##sys#extend-macro-environment
'condition-case
`((else . ,(##sys#primitive-alias 'else))
(memv . ,(##sys#primitive-alias 'memv)))
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax 'condition-case form '(_ _ . _))
(let ((exvar (r 'exvar))
(kvar (r 'kvar))
(%and (r 'and))
(%memv (r 'memv))
(%else (r 'else)))
(define (parse-clause c)
(let* ((var (and (symbol? (car c)) (car c)))
(kinds (if var (cadr c) (car c)))
(body (if var
`(##core#let ((,var ,exvar)) ,@(cddr c))
`(##core#let () ,@(cdr c)))))
(if (null? kinds)
`(,%else ,body)
`((,%and ,kvar ,@(map (lambda (k)
`(,%memv (##core#quote ,k) ,kvar)) kinds))
,body ) ) ) )
`(,(r 'handle-exceptions) ,exvar
(##core#let ((,kvar (,%and (##sys#structure? ,exvar
(##core#quote condition))
(##sys#slot ,exvar 1))))
,(let ((clauses (map parse-clause (cddr form))))
`(,(r 'cond)
,@clauses
,@(if (assq %else clauses)
`() ; Don't generate two else clauses
`((,%else (##sys#signal ,exvar)))) )) )
,(cadr form))))))
;;; SRFI-9:
(##sys#extend-macro-environment
'define-record-type
`((getter-with-setter . ,(##sys#primitive-alias 'getter-with-setter)))
(##sys#er-transformer
(lambda (form r c)
(##sys#check-syntax
'define-record-type
form
'(_ variable #(variable 1) variable . _))
(let* ((t (cadr form))
(conser (caddr form))
(pred (cadddr form))
(slots (cddddr form))
(%define (r 'define))
(%getter-with-setter (r 'getter-with-setter))
(vars (cdr conser))
(x (r 'x))
(y (r 'y))
(slotnames (map car slots)))
`(##core#begin
(,%define ,conser
(##sys#make-structure
(##core#quote ,t)
,@(map (lambda (sname)
(if (memq sname vars)
sname
'(##core#undefined) ) )
slotnames) ) )
(,%define (,pred ,x) (##sys#structure? ,x (##core#quote ,t)))
,@(let loop ([slots slots] [i 1])
(if (null? slots)
'()
(let* ((slot (car slots))
(settable (pair? (cddr slot)))
(setr (and settable (caddr slot)))
(ssetter (and (pair? setr)
(pair? (cdr setr))
(c 'setter (car setr))
(cadr setr)))
(get `(##core#lambda
(,x)
(##core#check
(##sys#check-structure
,x
(##core#quote ,t)
(##core#quote ,(cadr slot))))
(##sys#block-ref ,x ,i) ) )
(set (and settable
`(##core#lambda
(,x ,y)
(##core#check
(##sys#check-structure
,x
(##core#quote ,t)
(##core#quote ,ssetter)))
(##sys#block-set! ,x ,i ,y)) )))
`((,%define
,(cadr slot)
,(if (and ssetter (c ssetter (cadr slot)))
`(,%getter-with-setter ,get ,set)
get))
,@(if settable
(if ssetter
(if (not (c ssetter (cadr slot)))
`(((##sys#setter ##sys#setter) ,ssetter ,set))
'())
`((,%define ,setr ,set)))
'())
,@(loop (cdr slots) (add1 i)) ) ) ) ) ) ) ) ) )
;;; SRFI-26:
(##sys#extend-macro-environment
'cut
`((apply . ,(##sys#primitive-alias 'apply)))
(##sys#er-transformer
(lambda (form r c)
(let ((%<> (r '<>))
(%<...> (r '<...>))
(%apply (r 'apply)))
(when (null? (cdr form))
(syntax-error 'cut "you need to supply at least a procedure" form))
(let loop ([xs (cdr form)] [vars '()] [vals '()] [rest #f])
(if (null? xs)
(let ([rvars (reverse vars)]
[rvals (reverse vals)] )
(if rest
(let ([rv (r (gensym))])
`(##core#lambda
(,@rvars . ,rv)
(,%apply ,(car rvals) ,@(cdr rvals) ,rv) ) )
;;XXX should we drop the begin?
`(##core#lambda ,rvars ((##core#begin ,(car rvals)) ,@(cdr rvals)) ) ) )
(cond ((c %<> (car xs))
(let ([v (r (gensym))])
(loop (cdr xs) (cons v vars) (cons v vals) #f) ) )
((c %<...> (car xs))
(if (null? (cdr xs))
(loop '() vars vals #t)
(syntax-error 'cut
"tail patterns after <...> are not supported"
form)))