Logtalk reference manual
Built-in predicate: threaded_exit/1-2
Contents > Reference Manual > Built-in Predicates > threaded_exit/1-2

## threaded_exit/1-2

#### Description

    threaded_exit(Goal)
    threaded_exit(Goal, Tag)

Retrieves the result of proving `Goal` in a new thread. This predicate blocks execution until the reply is sent to the this message queue by the thread executing the goal. When there is no thread proving the goal, the predicate generates an exception. This predicate is non-deterministic, providing access to any alternative solutions of its argument.

The argument of this predicate should be a variant of the argument of the corresponding `threaded_call/1` call. When the predicate argument is subsumed by the `threaded_call/1` call argument, the `threaded_exit/1` call will succeed iff its argument is a solution of the (more general) goal.

The variant `threaded_exit/2` accepts a threaded call identifier tag generated by the calls to the `threaded_call/2` and `threaded_once/2` predicates. Tags shall be regarded as an opaque term; users shall not rely on its type.

#### Template and modes

    threaded_exit(+callable)
    threaded_exit(+callable, +nonvar)

#### Errors

Goal is a variable:
  `instantiation_error`
Goal is neither a variable nor a callable term:
  `type_error(callable, Goal)`
no thread is running for proving Goal:
  `existence_error(goal_thread, Goal)`
Tag is a variable:
  `instantiation_error`

#### Examples

To retrieve an asynchronous goal proof result:
  `threaded_exit(Goal)`
To retrieve an asynchronous message to self result:
  `threaded_exit(::Goal)`
To retrieve an asynchronous message result:
  `threaded_exit(Object::Goal)`