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1 | ;;; srfi-111.scm -- SRFI 111 Boxes |
2 | ||
3 | ;; Copyright (C) 2014 Free Software Foundation, Inc. | |
4 | ;; | |
5 | ;; This library is free software; you can redistribute it and/or | |
6 | ;; modify it under the terms of the GNU Lesser General Public | |
7 | ;; License as published by the Free Software Foundation; either | |
8 | ;; version 3 of the License, or (at your option) any later version. | |
9 | ;; | |
10 | ;; This library is distributed in the hope that it will be useful, | |
11 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | ;; Lesser General Public License for more details. | |
14 | ;; | |
15 | ;; You should have received a copy of the GNU Lesser General Public | |
16 | ;; License along with this library; if not, write to the Free Software | |
17 | ;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
18 | ||
19 | (define-module (srfi srfi-111) | |
20 | #:use-module (srfi srfi-9) | |
21 | #:use-module (srfi srfi-9 gnu) | |
22 | #:export (box box? unbox set-box!)) | |
23 | ||
24 | (cond-expand-provide (current-module) '(srfi-111)) | |
25 | ||
26 | (define-record-type <box> | |
27 | (box value) | |
28 | box? | |
29 | (value unbox set-box!)) | |
30 | ||
31 | (set-record-type-printer! <box> | |
32 | (lambda (box port) | |
33 | (display "#<box " port) | |
34 | (display (number->string (object-address box) 16) port) | |
35 | (display " value: ") | |
36 | (write (unbox box) port) | |
37 | (display ">" port))) |