lambda - Is there something like anonymous predicates in SWI Prolog?

Question

Can I define an anonymous predicate in SWI Prolog, bind it to a variable, and call it later? Something like this:

?- F = {(X, Y) :- Y is 2 * X}, call(F, 2.0, Y).

Answer 1

That′s what lambdas are for:

?- use_module(library(lambda)).
true.

?- F_2 = (X^Y^ ( Y is 2*X )), call(F_2,2.0,Y).
F_2 = X^4.0^(4.0 is 2*X),
Y = 4.0.