2675f711a3
* mes.c (scm_symbol_throw): New symbol.
* module/mes/catch.scm (catch, throw): Implement [WAS: syntactic sugar].
(make-exception, exception?, exception-key, exception-args): Remove.
* tests/catch.test ("catch", "catch 22"): Add tests.
* module/mes/base-0.scm: Include it.
48 lines
1.6 KiB
Scheme
48 lines
1.6 KiB
Scheme
;;; -*-scheme-*-
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;;; Mes --- Maxwell Equations of Software
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;;; Copyright © 2016 Jan Nieuwenhuizen <janneke@gnu.org>
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;;;
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;;; This file is part of Mes.
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;;;
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;;; 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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;;; 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 Mes. If not, see <http://www.gnu.org/licenses/>.
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(mes-use-module (mes let))
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(mes-use-module (mes fluids))
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(define %eh (make-fluid
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(lambda (key . args)
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(format (current-error-port) "unhandled exception: ~a ~a\n" key args)
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(exit 1))))
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(define (catch key thunk handler)
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(let ((previous-eh (fluid-ref %eh)))
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(with-fluid*
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%eh #f
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(lambda ()
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(call/cc
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(lambda (cc)
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(fluid-set! %eh
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(lambda (k . args)
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(let ((handler (if (or (eq? key #t) (eq? key k)) handler
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previous-eh)))
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(cc
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(lambda (x)
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(apply handler (cons k args)))))))
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(thunk)))))))
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(define (throw key . args)
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(let ((handler (fluid-ref %eh)))
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(apply handler (cons key args))))
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