From a7fff4f1922adc905bc3267cf40fbdf0b5d5b776 Mon Sep 17 00:00:00 2001
From: John Benediktsson <mrjbq7@gmail.com>
Date: Fri, 27 Jul 2012 09:12:29 -0700
Subject: [PATCH] sequences: slightly faster ?last.

---
 core/sequences/sequences.factor | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/core/sequences/sequences.factor b/core/sequences/sequences.factor
index f6cdebcc9a..211d5d71c2 100644
--- a/core/sequences/sequences.factor
+++ b/core/sequences/sequences.factor
@@ -177,7 +177,9 @@ PRIVATE>
 
 : ?first ( seq -- elt/f ) 0 swap ?nth ; inline
 : ?second ( seq -- elt/f ) 1 swap ?nth ; inline
-: ?last ( seq -- elt/f ) [ length 1 - ] [ ?nth ] bi ; inline
+: ?last ( seq -- elt/f )
+    [ length 1 - ] keep over 0 <
+    [ 2drop f ] [ nth-unsafe ] if ; inline
 
 MIXIN: virtual-sequence
 GENERIC: virtual-exemplar ( seq -- seq' )