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;;; srfi-9.scm --- define-record-type
;; Copyright (C) 2001, 2002, 2006 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
;;; Commentary:
;; This module exports the syntactic form `define-record-type', which
;; is the means for creating record types defined in SRFI-9.
;;
;; The syntax of a record type definition is:
;;
;; <record type definition>
;; -> (define-record-type <type name>
;; (<constructor name> <field tag> ...)
;; <predicate name>
;; <field spec> ...)
;;
;; <field spec> -> (<field tag> <accessor name>)
;; -> (<field tag> <accessor name> <modifier name>)
;;
;; <field tag> -> <identifier>
;; <... name> -> <identifier>
;;
;; Usage example:
;;
;; guile> (use-modules (srfi srfi-9))
;; guile> (define-record-type :foo (make-foo x) foo?
;; (x get-x) (y get-y set-y!))
;; guile> (define f (make-foo 1))
;; guile> f
;; #<:foo x: 1 y: #f>
;; guile> (get-x f)
;; 1
;; guile> (set-y! f 2)
;; 2
;; guile> (get-y f)
;; 2
;; guile> f
;; #<:foo x: 1 y: 2>
;; guile> (foo? f)
;; #t
;; guile> (foo? 1)
;; #f
;;; Code:
(define-module (srfi srfi-9)
:export-syntax (define-record-type))
(cond-expand-provide (current-module) '(srfi-9))
(define-macro (define-record-type type-name constructor/field-tag
predicate-name . field-specs)
`(begin
(define ,type-name
(make-record-type ',type-name ',(map car field-specs)))
(define ,(car constructor/field-tag)
(record-constructor ,type-name ',(cdr constructor/field-tag)))
(define ,predicate-name
(record-predicate ,type-name))
,@(map
(lambda (spec)
(cond
((= (length spec) 2)
`(define ,(cadr spec)
(record-accessor ,type-name ',(car spec))))
((= (length spec) 3)
`(begin
(define ,(cadr spec)
(record-accessor ,type-name ',(car spec)))
(define ,(caddr spec)
(record-modifier ,type-name ',(car spec)))))
(else
(error "invalid field spec " spec))))
field-specs)))
;;; srfi-9.scm ends here
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