source: trunk/j/src/org/armedbear/lisp/cond.lisp @ 11297

Last change on this file since 11297 was 11297, checked in by ehuelsmann, 13 years ago

Set Id keyword for expansion.

  • Property svn:eol-style set to native
  • Property svn:keywords set to Id
File size: 1.2 KB
Line 
1;;; cond.lisp
2;;;
3;;; Copyright (C) 2004 Peter Graves
4;;; $Id: cond.lisp 11297 2008-08-31 13:26:45Z ehuelsmann $
5;;;
6;;; This program is free software; you can redistribute it and/or
7;;; modify it under the terms of the GNU General Public License
8;;; as published by the Free Software Foundation; either version 2
9;;; of the License, or (at your option) any later version.
10;;;
11;;; This program is distributed in the hope that it will be useful,
12;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
13;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14;;; GNU General Public License for more details.
15;;;
16;;; You should have received a copy of the GNU General Public License
17;;; along with this program; if not, write to the Free Software
18;;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
19
20(in-package "SYSTEM")
21
22(defmacro cond (&rest clauses)
23  (if (endp clauses)
24      nil
25      (let ((clause (first clauses)))
26  (when (atom clause)
27    (error "COND clause is not a list: ~S" clause))
28  (let ((test (first clause))
29        (forms (rest clause)))
30    (if (endp forms)
31        (let ((n-result (gensym)))
32    `(let ((,n-result ,test))
33       (if ,n-result
34           ,n-result
35           (cond ,@(rest clauses)))))
36        `(if ,test
37       (progn ,@forms)
38       (cond ,@(rest clauses))))))))
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