Combinations of multiple lists - Prolog

Question

I need to find the combinations in a list of lists. For example, give the following list,

List = [[1, 2], [1, 2, 3]]

These should be the ou

Answer 1

For completeness, here is the augmented version of my comment-version. Note nilmemberd_t/2 which is inspired by memberd_t/2.

nilmemberd_t([], false).
nilmemberd_t([X|Xs], T) :-
   if_(nil_t(X), T = true, nilmemberd_t(Xs, T)).

nil_t([], true).
nil_t([_|_], false).

list_comb(List, []) :-
   nilmemberd_t(List, true).
list_comb(List, Ess) :-
   bagof(Es, maplist(member,Es,List), Ess).

Above version shows that "only" the first clause was missing in my comment response. Maybe even shorter with:

nilmemberd([[]|_]).
nilmemberd([[_|_]|Nils]) :-
   nilmemberd(Nils).

This should work for Prologs without constraints. With constraints, bagof/3 would have to be reconsidered since copying constraints is an ill-defined terrain.