From a84404bc0d2937baf143169ef59b08ff099e6444 Mon Sep 17 00:00:00 2001
From: Doug Coleman <doug.coleman@gmail.com>
Date: Thu, 14 Aug 2008 00:21:10 -0500
Subject: [PATCH] add some more utility words like when-empty

---
 extra/sequences/lib/lib.factor | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/extra/sequences/lib/lib.factor b/extra/sequences/lib/lib.factor
index 1167a3b7b4..17f855c264 100755
--- a/extra/sequences/lib/lib.factor
+++ b/extra/sequences/lib/lib.factor
@@ -211,8 +211,11 @@ PRIVATE>
 : insert-nth ( elt n seq -- seq' )
     swap cut-slice [ swap 1array ] dip 3append ;
 
-: if-seq ( seq quot1 quot2 -- )
-    [ f like ] 2dip if* ; inline
+: if-seq ( seq quot1 quot2 -- ) [ f like ] 2dip if* ; inline
+ 
+: if-empty ( seq quot1 quot2 -- ) swap if-seq ; inline
+
+: when-empty ( seq quot1 -- ) [ ] if-empty ; inline
+
+: unless-empty ( seq quot1 -- ) [ ] swap if-empty ; inline
 
-: if-empty ( seq quot1 quot2 -- )
-    swap if-seq ; inline