prune(A, B) :- union(A, B, B). union([X|Y],Z,W) :- member(X,Z), !, /* do not use next clauses */ union(Y,Z,W). union([X|Y],Z,[X|W]) :- union(Y,Z,W). union([],Z,Z). ?- prune([1,1,1,2],R).
Standard input is empty
prog.pl:12:4: syntax error: . or operator expected after expression 1 error(s) compilation failed
Standard output is empty