From e96f5a6efdf6634eee5aaa6a38b024fd3772ef67 Mon Sep 17 00:00:00 2001 From: Rob Browning Date: Sun, 20 Jun 2004 14:19:59 +0000 Subject: [PATCH] new file. --- srfi/srfi-31.scm | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) create mode 100644 srfi/srfi-31.scm diff --git a/srfi/srfi-31.scm b/srfi/srfi-31.scm new file mode 100644 index 000000000..cc9709117 --- /dev/null +++ b/srfi/srfi-31.scm @@ -0,0 +1,34 @@ +;;; srfi-34.scm --- Time/Date Library + +;; Copyright (C) 2004 Free Software Foundation, Inc. +;; +;; This library is free software; you can redistribute it and/or +;; modify it under the terms of the GNU Lesser General Public +;; License as published by the Free Software Foundation; either +;; version 2.1 of the License, or (at your option) any later version. +;; +;; This library 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 +;; Lesser General Public License for more details. +;; +;; You should have received a copy of the GNU Lesser General Public +;; License along with this library; if not, write to the Free Software +;; Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + +;;; Original author: Rob Browning + +(define-module (srfi srfi-31) + :export-syntax (rec)) + +(define-macro (rec arg-form . body) + (cond + ((and (symbol? arg-form) (= 1 (length body))) + ;; (rec S (cons 1 (delay S))) + `(letrec ((,arg-form ,(car body))) + ,arg-form)) + ;; (rec (f x) (+ x 1)) + ((list? arg-form) + `(letrec ((,(car arg-form) (lambda ,(cdr arg-form) ,@body))) + ,(car arg-form))) + (else "syntax error in rec form" `(rec ,arg-form ,@body)))) -- 2.20.1