\\+/1 — The Logtalk Handbook v3.47.0 documentation

# `\\+/1`

## Description

    \+ Goal

Not-provable meta-predicate. True iff `call(Goal)` is false. This built-in meta-predicate is declared as a private method and thus cannot be used as a message to an object.

## Modes and number of proofs

    \+ +callable - zero_or_one

## Errors

`Goal` is a variable:
`instantiation_error`
`Goal` is neither a variable nor a callable term:
`type_error(callable, Goal)`

## Examples

Not-provable goal in the context of the object or category containing the call:
`\+ Goal`
Not-provable goal sent as a message to self:
`\+ ::Goal`
Not-provable goal sent as a message to an explicit object:
`\+ Object::Goal`

See also

call/1-N, ignore/1, once/1