From 68b662c44ce8444baba29b40eceef73e80f27f1d Mon Sep 17 00:00:00 2001
From: John Benediktsson <mrjbq7@gmail.com>
Date: Sat, 13 Dec 2014 16:01:20 -0800
Subject: [PATCH] heaps: make data-first throw on empty.

---
 basis/heaps/heaps.factor | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/basis/heaps/heaps.factor b/basis/heaps/heaps.factor
index 2706b10f36..27b53860ff 100644
--- a/basis/heaps/heaps.factor
+++ b/basis/heaps/heaps.factor
@@ -62,7 +62,7 @@ M: heap heap-size ( heap -- n )
     data>> nth-unsafe { entry } declare ; inline
 
 : data-first ( heap -- entry )
-    0 swap data-nth ; inline
+    data>> first ; inline
 
 : data-set-nth ( entry n heap -- )
     [ [ >>index ] keep ] dip data>> set-nth-unsafe ; inline