=/2
Module: builtins
=/2 — unify two terms
\=/2 — test if two items are non-unifiable
FORMS
Arg1 = Arg2
Arg1 \= Arg2
DESCRIPTION
The procedure =/2 calls the Prolog unifier to unify Arg1 and Arg2, binding variables if necessary. The occurs check is not performed. =/2 is defined as if by the clause :
Term = Term.
If the two terms cannot be unified, = fails. The procedure \= succeeds if the two terms cannot be unified. This is different than the =\= and the \== procedures.
EXAMPLES
The following examples illustrate the use of =.
?- f(A,A)=f(a,B).
A=a
B=a
yes.
?- f(A,A)=f(a,b).
no.
?- X=f(X).
X=f(f(f(f(f(f(f(f(f(f(f(...)))))))))))
?- X\=1
no.
?- X\==1
X=_3
yes.
Note that in the next to last example, the depth of the printing is much deeper than shown here.