mes/base0-if.mes

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;;; -*-scheme-*-
;;; Mes --- Maxwell Equations of Software
;;; Copyright © 2016 Jan Nieuwenhuizen <janneke@gnu.org>
;;;
;;; base.mes: This file is part of Mes.
;;;
;;; Mes is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; Mes is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with Mes. If not, see <http://www.gnu.org/licenses/>.
(define (cons* x . rest)
(define (loop rest)
(if (null? (cdr rest)) (car rest) ;; IF
(cons (car rest) (loop (cdr rest)))))
(loop (cons x rest)))
(define-macro cond
(lambda clauses
(if (null? clauses) *unspecified* ;; IF
(if (null? (cdr clauses)) ;; IF
(list 'if (car (car clauses)) ;; IF
(cons* 'begin (car (car clauses)) (cdr (car clauses)))
*unspecified*)
(if (eq? (car (cadr clauses)) 'else) ;; IF
(list 'if (car (car clauses)) ;; IF
(cons* 'begin (car (car clauses)) (cdr (car clauses)))
(cons* 'begin *unspecified* (cdr (cadr clauses))))
(list 'if (car (car clauses)) ;; IF
(cons* 'begin (car (car clauses)) (cdr (car clauses)))
(cons* 'cond (cdr clauses)))))))) ;; IF