mirror of
https://git.savannah.gnu.org/git/guile.git
synced 2025-04-30 11:50:28 +02:00
0c65f52c6d
* module/ice-9/boot-9.scm: * module/ice-9/control.scm: * module/ice-9/futures.scm: * module/ice-9/optargs.scm: * module/ice-9/poll.scm: * module/ice-9/receive.scm: * module/ice-9/threads.scm: * module/ice-9/vlist.scm: * module/language/assembly/compile-bytecode.scm: * module/language/ecmascript/compile-tree-il.scm: * module/language/tree-il.scm: * module/oop/goops.scm: * module/oop/goops/simple.scm: * module/oop/goops/stklos.scm: * module/srfi/srfi-1.scm: * module/srfi/srfi-35.scm: * module/srfi/srfi-39.scm: * module/srfi/srfi-45.scm: * module/srfi/srfi-67/compare.scm: * module/sxml/match.scm: * module/system/repl/error-handling.scm: * module/system/repl/repl.scm: * module/system/vm/inspect.scm: * module/texinfo.scm: * module/web/server.scm: Use define-syntax-rule, where it makes sense.
78 lines
2.9 KiB
Scheme
78 lines
2.9 KiB
Scheme
;;; Beyond call/cc
|
|
|
|
;; Copyright (C) 2010, 2011 Free Software Foundation, Inc.
|
|
|
|
;;;; This library is free software; you can redistribute it and/or
|
|
;;;; modify it under the terms of the GNU Lesser General Public
|
|
;;;; License as published by the Free Software Foundation; either
|
|
;;;; version 3 of the License, or (at your option) any later version.
|
|
;;;;
|
|
;;;; This library 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
|
|
;;;; Lesser General Public License for more details.
|
|
;;;;
|
|
;;;; You should have received a copy of the GNU Lesser General Public
|
|
;;;; License along with this library; if not, write to the Free Software
|
|
;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
|
|
;;; Code:
|
|
|
|
(define-module (ice-9 control)
|
|
#:re-export (call-with-prompt abort-to-prompt
|
|
default-prompt-tag make-prompt-tag)
|
|
#:export (% abort shift reset shift* reset*))
|
|
|
|
(define (abort . args)
|
|
(apply abort-to-prompt (default-prompt-tag) args))
|
|
|
|
(define-syntax %
|
|
(syntax-rules ()
|
|
((_ expr)
|
|
(call-with-prompt (default-prompt-tag)
|
|
(lambda () expr)
|
|
default-prompt-handler))
|
|
((_ expr handler)
|
|
(call-with-prompt (default-prompt-tag)
|
|
(lambda () expr)
|
|
handler))
|
|
((_ tag expr handler)
|
|
(call-with-prompt tag
|
|
(lambda () expr)
|
|
handler))))
|
|
|
|
;; Each prompt tag has a type -- an expected set of arguments, and an unwritten
|
|
;; contract of what its handler will do on an abort. In the case of the default
|
|
;; prompt tag, we could choose to return values, exit nonlocally, or punt to the
|
|
;; user.
|
|
;;
|
|
;; We choose the latter, by requiring that the user return one value, a
|
|
;; procedure, to an abort to the prompt tag. That argument is then invoked with
|
|
;; the continuation as an argument, within a reinstated default prompt. In this
|
|
;; way the return value(s) from a default prompt are under the user's control.
|
|
(define (default-prompt-handler k proc)
|
|
(% (default-prompt-tag)
|
|
(proc k)
|
|
default-prompt-handler))
|
|
|
|
;; Kindly provided by Wolfgang J Moeller <wjm@heenes.com>, modelled
|
|
;; after the ones by Oleg Kiselyov in
|
|
;; http://okmij.org/ftp/Scheme/delim-control-n.scm, which are in the
|
|
;; public domain, as noted at the top of http://okmij.org/ftp/.
|
|
;;
|
|
(define-syntax-rule (reset . body)
|
|
(call-with-prompt (default-prompt-tag)
|
|
(lambda () . body)
|
|
(lambda (cont f) (f cont))))
|
|
|
|
(define-syntax-rule (shift var . body)
|
|
(abort-to-prompt (default-prompt-tag)
|
|
(lambda (cont)
|
|
((lambda (var) (reset . body))
|
|
(lambda vals (reset (apply cont vals)))))))
|
|
|
|
(define (reset* thunk)
|
|
(reset (thunk)))
|
|
|
|
(define (shift* fc)
|
|
(shift c (fc c)))
|