# HG changeset patch
# User haftmann
# Date 1133881630 -3600
# Node ID 02a830bab54214e0ece96d2d461bd5c089c60dbd
# Parent  0a733e11021a9e8fc581ccd27db38ccb5000528e
added 'dig' combinator

diff -r 0a733e11021a -r 02a830bab542 src/Pure/library.ML
--- a/src/Pure/library.ML	Tue Dec 06 09:04:09 2005 +0100
+++ b/src/Pure/library.ML	Tue Dec 06 16:07:10 2005 +0100
@@ -101,6 +101,7 @@
   val fold_index: (int * 'a -> 'b -> 'b) -> 'a list -> 'b -> 'b
   val foldr1: ('a * 'a -> 'a) -> 'a list -> 'a
   val foldl_map: ('a * 'b -> 'a * 'c) -> 'a * 'b list -> 'a * 'c list
+  val dig: ('a list -> 'a list) -> 'a list list -> 'a list list
   val unflat: 'a list list -> 'b list -> 'b list list
   val splitAt: int * 'a list -> 'a list * 'a list
   val dropwhile: ('a -> bool) -> 'a list -> 'a list
@@ -597,6 +598,10 @@
   | unflat [] [] = []
   | unflat _ _ = raise UnequalLengths;
 
+fun dig f xss =
+  unflat xss ((f o flat) xss);
+
+
 (*like Lisp's MAPC -- seq proc [x1, ..., xn] evaluates
   (proc x1; ...; proc xn) for side effects*)
 val seq = List.app;