include flatten/2 in library(lists).

git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@598 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
2002-09-17 16:43:00 +00:00
parent d6778dac3a
commit 7076ced716
2 changed files with 26 additions and 2 deletions
--- a/library/lists.yap
+++ b/library/lists.yap
@@ -25,7 +25,8 @@
 	sum_list/2,
 	suffix/2,
 	sumlist/2,
-        list_concat/2
+        list_concat/2,
+        flatten/2
 	]).


@@ -321,4 +322,12 @@ list_concat([H|T], [H|Lf], Li) :-



-
+%
+% flatten a list
+%
+flatten(X,Y) :- flatten_list(X,Y,[]).
+ 
+flatten_list([]) --> !.
+flatten_list([H|T]) --> !, flatten_list(H),flatten_list(T).
+flatten_list(H) --> [H].
+