sequences: add sigma and count

2008-07-03 12:24:16 -05:00 · 2008-07-03 12:24:16 -05:00 · e815494578
parent a1a252320a
commit e815494578
1 changed files with 5 additions and 0 deletions
--- a/core/sequences/sequences.factor
+++ b/core/sequences/sequences.factor
@ -722,3 +722,8 @@ PRIVATE>
        dup [ length ] map infimum
        swap [ [ nth-unsafe ] with { } map-as ] curry { } map-as
    ] unless ;
+
+: sigma ( seq quot -- n ) [ + ] compose 0 swap reduce ; inline
+
+: count ( seq quot -- n ) [ 1 0 ? ] compose sigma ; inline
+