This predicate behaves as
call(Goal) but it is not re-executable.
This built-in meta-predicate is declared as a private method and thus
cannot be used as a message to an object.
This meta-predicate is opaque to cuts in its argument.
Modes and number of proofs
once(+callable) - zero_or_one
Goalis a variable:
Goalis neither a variable nor a callable term:
Call a goal deterministically in the context of the object or category containing the call:
To send a goal as a non-backtracable message to self:
To send a goal as a non-backtracable message to an explicit object: