sequences.extras: adding "arg-where".

diff --git a/extra/sequences/extras/extras.factor b/extra/sequences/extras/extras.factor
index 2f1978950f296df759e41de264743c44550b04bd..2d48f3fc03c465199bbc74e68638498d0860b523 100644 (file)
--- a/extra/sequences/extras/extras.factor
+++ b/extra/sequences/extras/extras.factor
@@ -271,3 +271,7 @@ INSTANCE: odds immutable-sequence
 
 : arg-min ( seq -- n )
     dup length iota zip [ first-unsafe ] infimum-by second ;
+
+: arg-where ( ... seq quot: ( ... elt -- ... ? ) -- ... indices )
+    [ dup length iota zip ] dip
+    [ first-unsafe ] prepose filter values ; inline