new file: list and set utilities

Salvador Abreu
1 parent 2c862ae2
Showing 1 changed file with 12 additions and 0 deletions Show diff stats
fz/util.pl
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+% == No, Emacs this is -*-Prolog-*- code, not what you thought... =============
+
+% -- utility predicates -------------------------------------------------------
+
+% -- subset (SUB, SET, REST) --------------------------------------------------
+    
+subset(L, L, []).
+subset(S, [H|T], R) :- subset_aux(T, H, S, R).
+
+   subset_aux(S, R, S, [R]).
+   subset_aux([H|T], R1, S, [R1|R]) :- subset_aux(T, H, S, R).
+   subset_aux([H|T], X, [X|S], R) :- subset_aux(T, H, S, R).
@@ -0,0 +1,12 @@		@@ -0,0 +1,12 @@
	1	+% == No, Emacs this is --Prolog-- code, not what you thought... =============
	2	+
	3	+% -- utility predicates -------------------------------------------------------
	4	+
	5	+% -- subset (SUB, SET, REST) --------------------------------------------------
	6	+
	7	+subset(L, L, []).
	8	+subset(S, [H\|T], R) :- subset_aux(T, H, S, R).
	9	+
	10	+ subset_aux(S, R, S, [R]).
	11	+ subset_aux([H\|T], R1, S, [R1\|R]) :- subset_aux(T, H, S, R).
	12	+ subset_aux([H\|T], X, [X\|S], R) :- subset_aux(T, H, S, R).