Dom is the current domain (see in/2) of Var. This predicate is
useful if you want to reason about domains. It is not needed if
you only want to display remaining domains; instead, separate your
model from the search part and let the toplevel display this
information via residual goals.
For example, to implement a custom labeling strategy, you may need
to inspect the current domain of a finite domain variable. With the
following code, you can convert a finite domain to a list of
integers:
dom_integers(D, Is) :- phrase(dom_integers_(D), Is).
dom_integers_(I) --> { integer(I) }, [I].
dom_integers_(L..U) --> { numlist(L, U, Is) }, Is.
dom_integers_(D1\/D2) --> dom_integers_(D1), dom_integers_(D2).
Example:
?- X in 1..5, X #\= 4, fd_dom(X, D), dom_integers(D, Is).
D = 1..3\/5,
Is = [1,2,3,5],
X in 1..3\/5.
