add ?first2

2008-02-11 16:21:16 -06:00 · 2008-02-11 16:21:16 -06:00 · 8db19c2ee5
parent 04dc25f87a
commit 8db19c2ee5
1 changed files with 4 additions and 0 deletions
--- a/extra/sequences/lib/lib.factor
+++ b/extra/sequences/lib/lib.factor
@ -178,6 +178,10 @@ PRIVATE>
 : ?third ( seq -- third/f ) 2 swap ?nth ; inline
 : ?fourth ( seq -- fourth/f ) 3 swap ?nth ; inline

+: ?first2 ( seq -- 1st/f 2nd/f ) dup ?first swap ?second ; inline
+: ?first3 ( seq -- 1st/f 2nd/f 3rd/f ) dup ?first2 rot ?third ; inline
+: ?first4 ( seq -- 1st/f 2nd/f 3rd/f 4th/f ) dup ?first3 roll ?fourth ; inline
+
 : accumulator ( quot -- quot vec )
    V{ } clone [ [ push ] curry compose ] keep ;