170 lines
5.4 KiB
Scheme
170 lines
5.4 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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(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 (assq 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 (assq x (cdr a)))))
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(define (assq-ref-env x a)
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(let ((e (assq x a)))
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(if (eq? e #f) '*undefined* (cdr e))))
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;; Page 13
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(define (evcon c a)
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(cond
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((null? c) *unspecified*)
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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-env m a)
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(cond
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((null? m) '())
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((not (pair? m)) (eval-env m a))
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(#t (cons (eval-env (car m) a) (evlis-env (cdr m) a)))))
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(define (apply-env fn x a)
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(cond
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((atom? fn)
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(cond
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((builtin? fn) (call fn x))
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((eq? fn 'call-with-values) (call call-with-values-env (append x (cons a '()))))
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((eq? fn 'current-module) a)))
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((eq? (car fn) 'lambda)
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(let ((p (pairlis (cadr fn) x a)))
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(eval-begin-env (cddr fn) (cons (cons '*closure* p) p))))
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((eq? (car fn) '*closure*)
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(let ((args (caddr fn))
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(body (cdddr fn))
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(a (cddr (cadr fn))))
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(let ((p (pairlis args x a)))
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(eval-begin-env body (cons (cons '*closure* p) p)))))
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;;((eq? (car fn) 'label) (apply-env (caddr fn) x (cons (cons (cadr fn) (caddr fn)) a)))
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(#t (apply-env (eval-env fn a) x a))))
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(define (eval-expand e a)
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(cond
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((eq? e '*undefined*) e)
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((symbol? e) (assq-ref-env e a))
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((atom? 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) 'syntax) (cadr e))
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((eq? (car e) 'begin) (eval-begin-env e a))
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((eq? (car e) 'lambda) (make-closure (cadr e) (cddr e) (assq '*closure* a)))
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((eq? (car e) '*closure*) e)
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((eq? (car e) 'if) (eval-if-env (cdr e) a))
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((eq? (car e) 'define) (env:define (cons (sexp:define e a) '()) a))
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((eq? (car e) 'define-macro) (env:define (env:macro (sexp:define e a)) a))
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((eq? (car e) 'set!) (set-env! (cadr e) (eval-env (caddr e) a) a))
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((eq? (car e) 'apply-env) (apply-env (eval-env (cadr e) a) (evlis-env (caddr e) a) a))
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((eq? (car e) 'unquote) (eval-env (cadr e) a))
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((eq? (car e) 'quasiquote) (eval-quasiquote (cadr e) (add-unquoters a)))
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(#t (apply-env (eval-env (car e) a) (evlis-env (cdr e) a) a))))
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(#t (apply-env (eval-env (car e) a) (evlis-env (cdr e) a) a))))
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(define (unquote x) (cons 'unquote x))
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(define (unquote-splicing x) (cons 'quasiquote x))
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(define %the-unquoters
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(cons
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(cons 'unquote unquote)
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(cons (cons 'unquote-splicing unquote-splicing) '())))
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(define (add-unquoters a)
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(cons %the-unquoters a))
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(define (eval-env e a)
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(eval-expand (macro-expand-env e a) a))
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(define (macro-expand-env e a)
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(if (pair? e) ((lambda (macro)
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(if macro (macro-expand-env (apply-env macro (cdr e) a) a)
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e))
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(lookup-macro (car e) a))
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e))
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(define (eval-begin-env e a)
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(if (null? e) *unspecified*
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(if (null? (cdr e)) (eval-env (car e) a)
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(begin
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(eval-env (car e) a)
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(eval-begin-env (cdr e) a)))))
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(define (eval-if-env e a)
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(if (eval-env (car e) a) (eval-env (cadr e) a)
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(if (pair? (cddr e)) (eval-env (caddr e) a))))
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(define (eval-quasiquote e a)
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(cond ((null? e) e)
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((atom? e) e)
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((eq? (car e) 'unquote) (eval-env (cadr e) a))
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((and (pair? (car e))
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(eq? (caar e) 'unquote-splicing))
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(append2 (eval-env (cadar e) a) (eval-quasiquote (cdr e) a)))
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(#t (cons (eval-quasiquote (car e) a) (eval-quasiquote (cdr e) a)))))
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(define (sexp:define e a)
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(if (atom? (cadr e)) (cons (cadr e) (eval-env (caddr e) a))
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(cons (caadr e) (eval-env (cons 'lambda (cons (cdadr e) (cddr e))) a))))
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(define (env:define a+ a)
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(set-cdr! a+ (cdr a))
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(set-cdr! a a+)
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(set-cdr! (assq '*closure* a) a))
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(define (env:macro name+entry)
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(cons
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(cons (car name+entry)
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(make-macro (car name+entry)
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(cdr name+entry)))
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'()))
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