module/ice-9/match.scm

   1 ;;; -*- mode: scheme; coding: utf-8; -*-
   2 ;;;
   3 ;;; Copyright (C) 2010, 2011, 2012 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 3 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 match)
  20   #:export (match
  21             match-lambda
  22             match-lambda*
  23             match-let
  24             match-let*
  25             match-letrec))
  26
  27 (define (error _ . args)
  28   ;; Error procedure for run-time "no matching pattern" errors.
  29   (apply throw 'match-error "match" args))
  30
  31 ;; Support for record matching.
  32
  33 (define-syntax slot-ref
  34   (syntax-rules ()
  35     ((_ rtd rec n)
  36      (struct-ref rec n))))
  37
  38 (define-syntax slot-set!
  39   (syntax-rules ()
  40     ((_ rtd rec n value)
  41      (struct-set! rec n value))))
  42
  43 (define-syntax is-a?
  44   (syntax-rules ()
  45     ((_ rec rtd)
  46      (and (struct? rec)
  47           (eq? (struct-vtable rec) rtd)))))
  48
  49 ;; Compared to Andrew K. Wright's `match', this one lacks `match-define',
  50 ;; `match:error-control', `match:set-error-control', `match:error',
  51 ;; `match:set-error', and all structure-related procedures.  Also,
  52 ;; `match' doesn't support clauses of the form `(pat => exp)'.
  53
  54 ;; Unmodified public domain code by Alex Shinn retrieved from
  55 ;; the Chibi-Scheme repository, commit 1206:acd808700e91.
  56 ;;
  57 ;; Note: Make sure to update `match.test.upstream' when updating this
  58 ;; file.
  59 (include-from-path "ice-9/match.upstream.scm")