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91 lines
2.7 KiB
Scheme
91 lines
2.7 KiB
Scheme
;;; srfi-9.scm --- define-record-type
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;; Copyright (C) 2001, 2002, 2006 Free Software Foundation, Inc.
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;;
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;; This library is free software; you can redistribute it and/or
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;; modify it under the terms of the GNU Lesser General Public
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;; License as published by the Free Software Foundation; either
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;; version 2.1 of the License, or (at your option) any later version.
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;;
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;; This library is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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;; Lesser General Public License for more details.
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;;
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;; You should have received a copy of the GNU Lesser General Public
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;; License along with this library; if not, write to the Free Software
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;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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;;; Commentary:
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;; This module exports the syntactic form `define-record-type', which
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;; is the means for creating record types defined in SRFI-9.
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;;
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;; The syntax of a record type definition is:
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;;
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;; <record type definition>
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;; -> (define-record-type <type name>
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;; (<constructor name> <field tag> ...)
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;; <predicate name>
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;; <field spec> ...)
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;;
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;; <field spec> -> (<field tag> <accessor name>)
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;; -> (<field tag> <accessor name> <modifier name>)
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;;
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;; <field tag> -> <identifier>
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;; <... name> -> <identifier>
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;;
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;; Usage example:
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;;
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;; guile> (use-modules (srfi srfi-9))
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;; guile> (define-record-type :foo (make-foo x) foo?
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;; (x get-x) (y get-y set-y!))
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;; guile> (define f (make-foo 1))
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;; guile> f
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;; #<:foo x: 1 y: #f>
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;; guile> (get-x f)
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;; 1
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;; guile> (set-y! f 2)
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;; 2
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;; guile> (get-y f)
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;; 2
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;; guile> f
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;; #<:foo x: 1 y: 2>
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;; guile> (foo? f)
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;; #t
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;; guile> (foo? 1)
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;; #f
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;;; Code:
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(define-module (srfi srfi-9)
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:export-syntax (define-record-type))
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(cond-expand-provide (current-module) '(srfi-9))
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(define-macro (define-record-type type-name constructor/field-tag
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predicate-name . field-specs)
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`(begin
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(define ,type-name
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(make-record-type ',type-name ',(map car field-specs)))
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(define ,(car constructor/field-tag)
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(record-constructor ,type-name ',(cdr constructor/field-tag)))
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(define ,predicate-name
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(record-predicate ,type-name))
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,@(map
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(lambda (spec)
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(cond
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((= (length spec) 2)
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`(define ,(cadr spec)
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(record-accessor ,type-name ',(car spec))))
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((= (length spec) 3)
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`(begin
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(define ,(cadr spec)
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(record-accessor ,type-name ',(car spec)))
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(define ,(caddr spec)
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(record-modifier ,type-name ',(car spec)))))
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(else
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(error "invalid field spec " spec))))
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field-specs)))
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;;; srfi-9.scm ends here
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