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;;; Sly
;;; Copyright (C) 2015 David Thompson <davet@gnu.org>
;;;
;;; This program is free software: you can redistribute it and/or
;;; modify it under the terms of the GNU General Public License as
;;; published by the Free Software Foundation, either version 3 of the
;;; License, or (at your option) any later version.
;;;
;;; This program 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
;;; General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with this program. If not, see
;;; <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;; Immutable record type syntax with keyword argument constructor,
;; field inheritance, and default field values.
;;
;;; Code:
(define-module (sly records)
#:use-module (srfi srfi-9)
#:export (define-record-type*))
(define-syntax-rule (define-record-type* type
constructor keyword-constructor
predicate
(field getter default) ...)
"Define a new, immutable record type named TYPE. PREDICATE is the
name of the procedure that tests if an object is of TYPE. A GETTER is
the name of the accessor for its respective FIELD. CONSTRUCTOR is the
name of the record type's low-level constructor that uses positional
arguments corresponding to the order in which the fields are
specified. KEYWORD-CONSTRUCTOR is the name of the high-level
constructor that uses keyword arguments for each FIELD whose values
correspond to the DEFAULT associated with that field. Additionally, a
special keyword, #:inherit, can be used to copy values from another
instance of TYPE and only change the fields that are explicitly
overridden."
(begin
(define-record-type type
(constructor field ...)
predicate
(field getter) ...)
(define keyword-constructor
(let ((default-record (constructor default ...)))
(lambda* (#:key (inherit default-record)
(field (getter inherit)) ...)
(constructor field ...))))))
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