diff --git a/srfi/srfi-31.scm b/srfi/srfi-31.scm new file mode 100644 index 000000000..eefd37344 --- /dev/null +++ b/srfi/srfi-31.scm @@ -0,0 +1,57 @@ +;;; srfi-34.scm --- Time/Date Library + +;; Copyright (C) 2004 Free Software Foundation, Inc. +;; +;; This program 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 2, or +;; (at your option) any later version. +;; +;; This program 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 this software; see the file COPYING. If not, write to +;; the Free Software Foundation, Inc., 59 Temple Place, Suite 330, +;; Boston, MA 02111-1307 USA +;; +;; As a special exception, the Free Software Foundation gives permission +;; for additional uses of the text contained in its release of GUILE. +;; +;; The exception is that, if you link the GUILE library with other files +;; to produce an executable, this does not by itself cause the +;; resulting executable to be covered by the GNU General Public License. +;; Your use of that executable is in no way restricted on account of +;; linking the GUILE library code into it. +;; +;; This exception does not however invalidate any other reasons why +;; the executable file might be covered by the GNU General Public License. +;; +;; This exception applies only to the code released by the +;; Free Software Foundation under the name GUILE. If you copy +;; code from other Free Software Foundation releases into a copy of +;; GUILE, as the General Public License permits, the exception does +;; not apply to the code that you add in this way. To avoid misleading +;; anyone as to the status of such modified files, you must delete +;; this exception notice from them. +;; +;; If you write modifications of your own for GUILE, it is your choice +;; whether to permit this exception to apply to your modifications. +;; If you do not wish that, delete this exception notice. + +(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)))) diff --git a/test-suite/tests/srfi-31.test b/test-suite/tests/srfi-31.test new file mode 100644 index 000000000..995fcd630 --- /dev/null +++ b/test-suite/tests/srfi-31.test @@ -0,0 +1,34 @@ +;;;; srfi-31.test --- Test suite for Guile's SRFI-31 functions. -*- scheme -*- +;;;; +;;;; Copyright (C) 2004 Free Software Foundation, Inc. +;;;; +;;;; This program 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 2, or (at your option) +;;;; any later version. +;;;; +;;;; This program 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 this software; see the file COPYING. If not, write to +;;;; the Free Software Foundation, Inc., 59 Temple Place, Suite 330, +;;;; Boston, MA 02111-1307 USA + +(use-modules (srfi srfi-31)) + +(with-test-prefix "rec special form" + + (pass-if "rec expressions" + (let ((ones-list (rec ones (cons 1 (delay ones))))) + (and (= 1 (car ones-list)) + (= 1 (car (force (cdr ones-list))))))) + + (pass-if "rec functions" + (let ((test-func (rec (add-upto n) + (if (positive? n) + (+ n (add-upto (- n 1))) + 0)))) + (= 15 (test-func 5)))))