nonmember(+Element, +List)

Succeeds if Element is not an element of the list List.

Description

Used to check that Element is not a member of the list List.

The definition of this Prolog library predicate is:

nonmember(Arg,[Arg|_]) :-
        !,
        fail.
nonmember(Arg,[_|Tail]) :-
        !,
        nonmember(Arg,Tail).
nonmember(_,[]).

This predicate does not perform any type testing functions.

Fails if Element is an element of the list List.

No.

Success:
  nonmember(q,[1,2,3,4,5,6,7]).

Fail:
  nonmember(1,[1,2,3]).
  nonmember(q,[1,2,2,X]). % X and q are unifiable