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;;; guile-2d
;;; Copyright (C) 2013 David Thompson <dthompson2@worcester.edu>
;;;
;;; Guile-2d 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.
;;;
;;; Guile-2d 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 program. If not, see
;;; <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;; Cooperative multi-tasking.
;;
;;; Code:
(define-module (2d coroutine)
#:export (coroutine
define-coroutine
wait)
#:replace (yield)
#:use-module (2d agenda))
(define (execute-coroutine thunk)
"Creates a procedure that can yield a continuation."
(define (handler cont callback . args)
(define (resume . args)
;; Call continuation that resumes the procedure.
(call-with-prompt 'coroutine-prompt
(lambda () (apply cont args))
handler))
(when (procedure? callback)
(apply callback resume args)))
;; Call procedure.
(call-with-prompt 'coroutine-prompt thunk handler))
;; emacs: (put 'coroutine 'scheme-indent-function 0)
(define-syntax-rule (coroutine body ...)
(begin
(agenda-schedule
(lambda ()
(execute-coroutine
(lambda () body ...))))))
;; emacs: (put 'define-coroutine 'scheme-indent-function 1)
(define-syntax define-coroutine
(syntax-rules ()
((_ (name . args) . body)
;; Outer define for the execute-coroutine call.
(define (name . args)
;; Make a new procedure with the same signature so that a
;; recursive procedure can be created without starting a new
;; coroutine with each call to itself.
(define (name . args) . body)
;; Coroutine time.
(execute-coroutine (lambda () (name . args)))))))
(define (yield callback)
"Yield continuation to a callback procedure."
(abort-to-prompt 'coroutine-prompt callback))
(define* (wait #:optional (delay 1))
"Yield coroutine and schdule the continuation to be run after delay
ticks."
(yield (lambda (resume) (agenda-schedule resume delay))))
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