:- use_module(lambda).
% foldl(Pred, Init, List, R).
%
foldl(_Pred, Val, [], Val).
foldl(Pred, Val, [H | T], Res) :-
call(Pred, Val, H, Val1),
foldl(Pred, Val1, T, Res).
fact(N, F) :-
numlist(2, N, L),
foldl(\X^Y^Z^(Z is X * Y), 1, L, F).