foldl(:Goal,
+List, +V0, -V)
foldl(P, [X11,...,X1n], ..., [Xm1,...,Xmn], V0, Vn) :-
P(X11, ..., Xm1, V0, V1),
...
P(X1n, ..., Xmn, V', Vn).
foldl(:Goal,
+List, +V0, -V)
foldl(P, [X11,...,X1n], ..., [Xm1,...,Xmn], V0, Vn) :-
P(X11, ..., Xm1, V0, V1),
...
P(X1n, ..., Xmn, V', Vn).