sequences.extras: add 2reduce-from

diff --git a/extra/sequences/extras/extras.factor b/extra/sequences/extras/extras.factor
index c6a03facf5997610c69760f587e614557c716dc0..ee670e3954763a7575297110047f47c7c98adae6 100644 (file)
--- a/extra/sequences/extras/extras.factor
+++ b/extra/sequences/extras/extras.factor
@@ -9,6 +9,9 @@ IN: sequences.extras
 : reduce-from ( ... seq identity quot: ( ... prev elt -- ... next ) i -- ... result )
     [ swap ] 2dip each-from ; inline
 
+: 2reduce-from ( ... seq1 seq2 identity quot: ( ... prev elt1 elt2 -- ... next ) i -- ... result )
+    [ -rot ] 2dip 2each-from ; inline
+
 :: subseq* ( from to seq -- subseq )
     seq length :> len
     from [ dup 0 < [ len + ] when ] [ 0 ] if*