# `threaded_engine_next_reified/2`

## Description

    threaded_engine_next_reified(Engine, Answer)

Retrieves an answer from an engine and signals it to start computing the next answer. This predicate always succeeds and blocks until an answer becomes available. Answers are returned using the terms `the(Answer)`, `no`, and `exception(Error)`.

Note

This predicate requires a backend Prolog compiler providing compatible multi-threading primitives. The value of the read-only engines flag is set to `supported` when that is the case.

## Modes and number of proofs

    threaded_engine_next_reified(@nonvar, ?nonvar) - one

## Errors

`Engine` is a variable:
`instantiation_error`
`Engine` is neither a variable nor the name of an existing engine:
`existence_error(engine, Engine)`

## Examples

    % get the next reified answer from the worker_1 engine:
    | ?- threaded_engine_next_reified(worker_1, Answer).

See also

threaded_engine_create/3, threaded_engine_next/2, threaded_engine_yield/1