At

https://www.swi-prolog.org/pldoc/doc_for?object=convlist/3

A Prologified lambda expression from library yall is passed. I wonder whether this works here?

Note that this predicate is best when you have to work on each list element by itself or have to check a conjunction (with short-circuiting exit) of a predicate over all list elements.

There is no way to pass state from one invocation of your predicate to the next, so performing max, min and any others is not possible (unless you do really special things with the one variable that you can pass to all invocations).

Use the neighboring foldl, scanl etc.

Example to explain maplist/2

verify/2:

if the first argument is known, check that the first argument is an integer < 4 otherwise check that the second argument is an integer < 4

verify(A,B) :- format("Received A = ~w, B = ~w\n",[A,B]), (\+var(A) -> integer(A), A<4; integer(B), B<4).

?- maplist(verify(X),[1,2,3,4,5,6]).

Received A = _22708, B = 1

Received A = _22708, B = 2

Received A = _22708, B = 3

Received A = _22708, B = 4

false.

?- maplist(verify(2),[1,2,3,4,5,6]).

Received A = 2, B = 1

Received A = 2, B = 2

Received A = 2, B = 3

Received A = 2, B = 4

Received A = 2, B = 5

Received A = 2, B = 6

true.

?- maplist(verify(6),[1,2,3,4,5,6]).

Received A = 6, B = 1

false.

The goal cannot be complex. Syntax restriction!

?- maplist((verify(6),verify(2)),[1,2,3,4,5,6]).

ERROR: Unknown procedure: (',')/3

It's a bit unsettling that you have to write verify(6) to have verify(6,X) be called with, for each call, the X coming from the list passed (in unspecified order!), but Prolog does not have a lambda notation, for example \X.verify(6,X).

uh..what if you wanted to pass some arguments to Goal, i.e. maplist(g(a), L)? Now will the arg from L be added as the first arg for the g/2 goal or the last...? (Yes, I can try it out, but I shouldn't have to!)