;;; -*-scheme-*-

;;; GNU Mes --- Maxwell Equations of Software
;;; Copyright © 2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
;;;
;;; This file is part of GNU Mes.
;;;
;;; GNU Mes 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.
;;;
;;; GNU Mes 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 GNU Mes.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;;; srfi-9.mes - GNU immutable records.

(define-macro (define-immutable-record-type type constructor+params predicate . fields)
  `(define-record-type ,type ,constructor+params ,predicate ,@(map (lambda (f) (list-head f 2)) fields)))

(define-macro (set-field o getters value)
  `(let ((getter ,(car getters)))
     (let* ((type (struct-vtable ,o))
            (name (record-type ,o))
            (set (getter ,o #t)))
       (define (field->value field)
         (if (eq? set field) ,value
             ((record-getter type field) ,o)))
       (let* ((fields (record-fields type))
              (values (map field->value fields)))
         (apply (record-constructor type name fields) values)))))