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?Term1 = ?Term2

Succeeds if Term1 and Term2 unify.
Term1
An arbitrary term.
Term2
An arbitrary term.

Description

Succeeds if the term Term1 unifies with the term Term2, otherwise it fails.

The unification procedure does not contain an occur check. Hence, cyclic structures can be created during unification. These cyclic structures may cause loops in attempting unification. eg. X = f(X,Y), Y = f(X,Y).

Modes and Determinism

Fail Conditions

Fails if Term1 does not unify with Term2.

Exceptions

(11) unify event
Term1 or Term2 contain an attributed variable and it is unified with a nonvariable.

Examples

   Success:
   atom = atom.
   atom = X.          (gives X = atom)
   X = atom.          (gives X = atom)
   f(1) = X.          (gives X = f(1))
   Y = X.             (gives Y = _g68, X = _g68)
   [1,X] = [Y,2].     (gives X = 2, Y = 1)
   [1,X|Y] = [W,2|Z]. (gives X = 2, Y = _g78,
   W = 1, Z = _g78)
   [1,A,2,B] = [C|D]. (gives A = _g80, B = _g88,
   C = 1, D = [_g80, 2, _g88])
   Fail:
   atom = neutron.
   1.0 = 1.
   [a|b] = [a,b].

See Also

== / 2, \= / 2