[ Control | The ECLiPSe Built-In Predicates | Reference Manual | Alphabetic Index ]

not +Goal

Succeeds if Goal cannot be satisfied (uses negation as failure).
+Goal
Atom or compound term.

Description

Used to fail if Goal succeeds. Uses the standard Prolog form of negation as failure.

To check whether a call Goal succeeds without binding variables, the call not not Goal can be used. Note that !/0 does not cut through not/1.

Fail Conditions

Fails if Goal succeeds.

Resatisfiable

No.

Examples

Success:
      not fail .
      not 1 == 2 .
      not X==1 .
      not not X = 1.
          % does not bind X
Fail:
      not(X=1).
      not(true).
      not(3 == 3).

See Also

\+ / 1, ~ / 1, -> / 2