From 1fa7e4dd02d5669f200f69ad12b73caa3ae530dc Mon Sep 17 00:00:00 2001
From: Andy Wingo <wingo@pobox.com>
Date: Wed, 13 Feb 2013 16:06:09 +0100
Subject: [PATCH] #f is a null pointer for glut callbacks

* figl/glut/types.scm (coerce-callback-pointer/ephemeral):
  (coerce-callback-pointer/sticky): Allow #f to indicate a null pointer.
---
 figl/glut/types.scm | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/figl/glut/types.scm b/figl/glut/types.scm
index 9a043f6..9d1befd 100644
--- a/figl/glut/types.scm
+++ b/figl/glut/types.scm
@@ -83,6 +83,8 @@
 
 (define (coerce-callback-pointer/ephemeral x return-type arg-types)
   (cond
+   ((not x)
+    ffi:%null-pointer)
    ((ffi:pointer? x)
     x)
    ((procedure? x)
@@ -98,6 +100,8 @@
 
 (define (coerce-callback-pointer/sticky x return-type arg-types)
   (cond
+   ((not x)
+    ffi:%null-pointer)
    ((ffi:pointer? x)
     x)
    ((procedure? x)
-- 
2.20.1