38 lines
1.5 KiB
Scheme
38 lines
1.5 KiB
Scheme
;;; -*-scheme-*-
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;;; GNU Mes --- Maxwell Equations of Software
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;;; Copyright © 2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
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;;;
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;;; This file is part of GNU Mes.
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;;;
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;;; GNU Mes is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Mes is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Mes. If not, see <http://www.gnu.org/licenses/>.
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;;; Commentary:
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;;; srfi-9.mes - GNU immutable records.
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(define-macro (define-immutable-record-type type constructor+params predicate . fields)
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`(define-record-type ,type ,constructor+params ,predicate ,@(map (lambda (f) (list-head f 2)) fields)))
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(define-macro (set-field o getters value)
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`(let ((getter ,(car getters)))
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(let ((type (record-type ,o))
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(set (getter ,o #t)))
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(define (field->value field)
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(if (eq? set field) ,value
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((record-getter type field) ,o)))
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(let* ((fields (record-fields type))
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(values (map field->value fields)))
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(apply (record-constructor type fields) values)))))
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