Prolog从列表中删除多个元素
问题描述：
我知道如何从列表中删除一个元素，但是有一种方法可以从列表中删除多个元素?例如，
I know how to remove an element from a list but is there a way to remove more than one elements from a list? For example,
deletelist([a,b,c,a,b],[a,c],X)
X = [b,b] % delete a and c from the list.
答
SWI-Prolog提供subtract/3:
SWI-Prolog offers subtract/3:
?- subtract([a,b,c,a,b], [a,c], X).
X = [b, b].
?- listing(subtract).
lists:subtract([], _, []) :- !.
lists:subtract([A|C], B, D) :-
memberchk(A, B), !,
subtract(C, B, D).
lists:subtract([A|B], C, [A|D]) :-
subtract(B, C, D).