Compatible Doclog docs for library(dif)
+/**
+Provides predicate dif/2. dif/2 is a constraint that is true only if both of its
+arguments are different terms.
+*/
+
:- module(dif, [dif/2]).
:- use_module(library(atts)).
@@ -38,6 +43,20 @@ verify_attributes(Var, Value, Goals) :-
% Probably the world's worst dif/2 implementation. I'm open to
% suggestions for improvement.
+%% dif(?X, ?Y).
+%
+% True iff X and Y are different terms. Unlike \\=/2, dif/2 is more declarative because if X and Y can
+% unify but they're not yet equal, the decision is delayed, and prevents X and Y to become equal later.
+% Examples:
+%
+% ?- dif(a, a).
+% false.
+% ?- dif(a, b).
+% true.
+% ?- dif(X, b).
+% dif:dif(X,b).
+% ?- dif(X, b), X = b.
+% false.
dif(X, Y) :-
X \== Y,
( X \= Y -> true
