sequences.extras: Make a <zip-index> for issue #745.

[factor.git] / extra / sequences / extras / extras.factor

diff --git a/extra/sequences/extras/extras.factor b/extra/sequences/extras/extras.factor
index 0d37e3e14d118f96a3c9de09c4258144c6c767b2..fbe65dc2ee477ef1e8bcbed358451a3d777c3b9c 100644 (file)
--- a/extra/sequences/extras/extras.factor
+++ b/extra/sequences/extras/extras.factor
@@ -774,3 +774,40 @@ M: step-slice length
     zero? [ 1 + ] unless ; inline
 
 INSTANCE: step-slice virtual-sequence
+
+: 2nested-each ( seq1 seq2 quot -- )
+    swapd '[
+        swap _ with each
+    ] with each ; inline
+
+: 3nested-each ( seq1 seq2 seq3 quot -- )
+    [ spin ] dip '[
+        -rot [
+            swap _ with with each
+        ] with with each
+    ] with with each ; inline
+
+: 2nested-map ( seq1 seq2 quot -- seq )
+    2over [ length ] bi@ * reach
+    [
+        new-resizable
+        [ [ push ] curry compose 2nested-each ] keep
+    ] keep like ; inline
+
+: 3nested-map ( seq1 seq2 seq3 quot -- seq )
+    3 nover [ length ] tri@ * * 5 npick
+    [
+        new-resizable
+        [ [ push ] curry compose 3nested-each ] keep
+    ] keep like ; inline
+
+TUPLE: virtual-zip-index seq ;
+
+C: <zip-index> virtual-zip-index
+
+M: virtual-zip-index length seq>> length ; inline
+
+M: virtual-zip-index nth-unsafe
+    over [ seq>> nth-unsafe ] [ 2array ] bi* ; inline
+
+INSTANCE: virtual-zip-index immutable-sequence