226 lines
6.7 KiB
Scheme
226 lines
6.7 KiB
Scheme
;;; -*-scheme-*-
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;;; Mes --- Maxwell Equations of Software
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;;; Copyright © 2016 Jan Nieuwenhuizen <janneke@gnu.org>
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;;;
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;;; mes.mes: This file is part of Mes.
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;;;
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;;; Mes is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; Mes is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with Mes. If not, see <http://www.gnu.org/licenses/>.
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;; The Maxwell Equations of Software -- John McCarthy page 13
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;; http://www.softwarepreservation.org/projects/LISP/book/LISP%201.5%20Programmers%20Manual.pdf
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;; (define (caar x) (car (car x)))
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;; (define (cadr x) (car (cdr x)))
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;; (define (cdar x) (cdr (car x)))
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;; (define (cddr x) (cdr (cdr x)))
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;; (define (caadr x) (car (car (cdr x))))
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;; (define (caddr x) (car (cdr (cdr x))))
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;; (define (cddar x) (cdr (cdr (car x))))
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;; (define (cdadr x) (cdr (car (cdr x))))
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;; (define (cadar x) (car (cdr (car x))))
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;; (define (cdddr x) (cdr (cdr (cdr x))))
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;; ;; Page 12
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;; (define (pairlis x y a)
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;; ;;(debug "pairlis x=~a y=~a a=~a\n" x y a)
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;; (cond
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;; ((null? x) a)
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;; ((atom? x) (cons (cons x y) a))
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;; (#t (cons (cons (car x) (car y))
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;; (pairlis (cdr x) (cdr y) a)))))
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;; (define (assoc x a)
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;; ;;(stderr "assoc x=~a\n" x)
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;; ;;(debug "assoc x=~a a=~a\n" x a)
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;; (cond
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;; ((null? a) #f)
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;; ((eq? (caar a) x) (car a))
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;; (#t (assoc x (cdr a)))))
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;; ;; Page 13
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;; (define (eval-quote fn x)
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;; ;(debug "eval-quote fn=~a x=~a" fn x)
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;; (apply fn x '()))
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(define (evcon c a)
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;;(debug "evcon c=~a a=~a\n" c a)
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(cond
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;; single-statement cond
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;; ((eval (caar c) a) (eval (cadar c) a))
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((eval (caar c) a)
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(cond ((null? (cddar c)) (eval (cadar c) a))
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(#t (eval (cadar c) a)
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(evcon
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(cons (cons #t (cddar c)) '())
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a))))
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(#t (evcon (cdr c) a))))
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(define (evlis m a)
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;;(debug "evlis m=~a a=~a\n" m a)
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;; (display 'mes-evlis:)
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;; (display m)
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;; (newline)
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(cond
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((null? m) '())
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(#t (cons (eval (car m) a) (evlis (cdr m) a)))))
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(define (apply fn x a)
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;; (display 'mes-apply:)
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;; (newline)
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;; (display 'fn:)
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;; (display fn)
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;; (newline)
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;; (display 'builtin:)
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;; (display (builtin? fn))
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;; (newline)
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;; (display 'x:)
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;; (display x)
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;; (newline)
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(cond
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((atom? fn)
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(cond
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((eq? fn 'current-module) ;; FIXME
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(c:apply current-module '() a))
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((builtin? fn)
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(call fn x))
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(#t (apply (eval fn a) x a))))
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((eq? (car fn) 'lambda)
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(begin-env (cddr fn) (pairlis (cadr fn) x a)))
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((eq? (car fn) 'label) (apply (caddr fn) x (cons (cons (cadr fn)
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(caddr fn)) a)))))
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(define (begin-env body a)
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(cond ((null? body) *unspecified*)
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((null? (cdr body)) (eval (car body) a))
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(#t (eval (car body) a)
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(begin-env (cdr body) a))))
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(define (set-env! x e a)
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(set-cdr! (assoc x a) e))
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(define (eval e a)
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;;(debug "eval e=~a a=~a\n" e a)
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;;(debug "eval (atom? ~a)=~a\n" e (atom? e))
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;; (display 'mes-eval:)
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;; (display e)
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;; (newline)
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;; (display 'a:)
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;; (display a)
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;; (newline)
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(cond
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((number? e) e)
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((eq? e #t) #t)
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((eq? e #f) #f)
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((atom? e) (cdr (assoc e a)))
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((builtin? e) e)
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((atom? (car e))
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(cond
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((eq? (car e) 'quote) (cadr e))
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((eq? (car e) 'lambda) e)
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((eq? (car e) 'set!) (set-env! (cadr e) (caddr e) a))
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((eq? (car e) 'unquote) (eval (cadr e) a))
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((eq? (car e) 'quasiquote) (eval-quasiquote (cadr e) a))
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((eq? (car e) 'cond) (evcon (cdr e) a))
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((pair? (assoc (car e) (cdr (assoc '*macro* a))))
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(c:eval
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(c:apply
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(cdr (assoc (car e) (cdr (assoc '*macro* a))))
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(cdr e)
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a)
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a))
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(#t (apply (car e) (evlis (cdr e) a) a))))
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(#t (apply (car e) (evlis (cdr e) a) a))))
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(define (eval-quasiquote e a)
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;; (display 'mes-eval-quasiquote:)
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;; (display e)
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;; (newline)
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(cond ((null? e) e)
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((atom? e) e)
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((atom? (car e)) (cons (car e) (eval-quasiquote (cdr e) a)))
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((eq? (caar e) 'unquote) (cons (eval (cadar e) a) '()))
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((eq? (caar e) 'quote) (cons (cadar e) '()))
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((eq? (caar e) 'quasiquote) (cons (cadar e) '()))
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(#t (cons (car e) (eval-quasiquote (cdr e) a)))))
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;; readenv et al works, but slows down dramatically
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(define (DISABLED-readenv a)
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(readword (getchar) '() a))
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(define (readword c w a)
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;; (display 'mes-readword:)
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;; (display c)
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;; (newline)
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(cond ((eq? c -1) ;; eof
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(cond ((eq? w '()) '())
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(#t (lookup w a))))
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((eq? c 10) ;; \n
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(cond ((eq? w '()) (readword (getchar) w a))
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;; DOT ((eq? w '(*dot*)) (car (readword (getchar) '() a)))
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(#t (lookup w a))))
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((eq? c 32) ;; \space
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(readword 10 w a))
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((eq? c 40) ;; (
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(cond ((eq? w '()) (readlis a))
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(#t (ungetchar c) (lookup w a))))
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((eq? c 41) ;; )
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(cond ((eq? w '()) (ungetchar c) w)
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(#t (ungetchar c) (lookup w a))))
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((eq? c 39) ;; '
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(cond ((eq? w '())
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(cons (lookup (cons c '()) a)
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(cons (readword (getchar) w a) '())))
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(#t (ungetchar c) (lookup w a))))
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((eq? c 59) ;; ;
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(readcomment c)
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(readword 10 w a))
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((eq? c 35) ;; #
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(cond ((eq? (peekchar) 33) ;; !
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(getchar)
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(readblock (getchar))
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(readword 10 w a))
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(#t (readword (getchar) (append w (cons c '())) a))))
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(#t (readword (getchar) (append w (cons c '())) a))))
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(define (readblock c)
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;; (display 'mes-readblock:)
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;; (display c)
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;; (newline)
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(cond ((eq? c 33) (cond ((eq? (peekchar) 35) (getchar))
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(#t (readblock (getchar)))))
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(#t (readblock (getchar)))))
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(define (eat-whitespace)
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(cond ((eq? (peekchar) 10) (getchar) (eat-whitespace))
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((eq? (peekchar) 32) (getchar) (eat-whitespace))
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((eq? (peekchar) 35) (getchar) (eat-whitespace))
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(#t #t)))
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(define (readlis a)
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;; (display 'mes-readlis:)
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;; (newline)
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(eat-whitespace)
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(cond ((eq? (peekchar) 41) ;; )
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(getchar)
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'())
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;; TODO *dot*
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(#t (cons (readword (getchar) '() a) (readlis a)))))
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(define (readcomment c)
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(cond ((eq? c 10) ;; \n
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c)
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(#t (readcomment (getchar)))))
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