ice-9/list.scm

   1 ;;;; List functions not provided in R5RS or srfi-1
   2
   3 ;;; Copyright (C) 2003, 2006 Free Software Foundation, Inc.
   4 ;;;
   5 ;; This library is free software; you can redistribute it and/or
   6 ;; modify it under the terms of the GNU Lesser General Public
   7 ;; License as published by the Free Software Foundation; either
   8 ;; version 2.1 of the License, or (at your option) any later version.
   9 ;;
  10 ;; This library is distributed in the hope that it will be useful,
  11 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 ;; Lesser General Public License for more details.
  14 ;;
  15 ;; You should have received a copy of the GNU Lesser General Public
  16 ;; License along with this library; if not, write to the Free Software
  17 ;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18
  19 (define-module (ice-9 list)
  20   :export (rassoc rassv rassq))
  21
  22 (define (generic-rassoc key alist =)
  23   (let loop ((ls alist))
  24       (and (not (null? ls))
  25            (if (= key (cdar ls))
  26                (car ls)
  27                (loop (cdr ls))))))
  28
  29 (define (rassoc key alist . =)
  30   (generic-rassoc key alist (if (null? =) equal? (car =))))
  31
  32 (define (rassv key alist)
  33   (generic-rassoc key alist eqv?))
  34
  35 (define (rassq key alist)
  36   (generic-rassoc key alist eq?))