mes/base0-cond.mes

32 lines
1.2 KiB
Scheme

;;; -*-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-macro (if expr then . else)
(list 'cond ;; COND
(list expr then)
(list #t (list 'cond (list (pair? else) ;; COND
(cons (cons 'lambda (cons '() (cons (cons 'begin (cons *unspecified* else)) '()))) '()))))))
(define (cons* x . rest)
(define (loop rest)
(cond ((null? (cdr rest)) (car rest)) ;; COND
(#t (cons (car rest) (loop (cdr rest))))))
(loop (cons x rest)))