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[gacela.git] / src / utils.scm

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+;;; Gacela, a GNU Guile extension for fast games development
+;;; Copyright (C) 2016 by Javier Sancho Fernandez <jsf at jsancho dot org>
+;;;
+;;; This program 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.
+;;;
+;;; This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+(define-module (gacela utils)
+  #:export (make-producer))
+
+(define (make-producer body)
+  (define resume #f)
+  (lambda (real-send)
+    (define send-to real-send)
+    (define (send value-to-send)
+      (set! send-to
+       (call/cc
+        (lambda (k)
+          (set! resume k)
+          (send-to value-to-send)))))
+    (if resume
+       (resume real-send)
+       (body send))))