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.. rst-class:: align-right

built-in predicate

.. index:: pair: threaded_engine/1; Built-in predicate .. _predicates_threaded_engine_1:

threaded_engine/1

Description

::

threaded_engine(Engine)

Enumerates, by backtracking, all existing engines. Engine names shall be regarded as opaque terms; users shall not rely on their type.

.. note::

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

Modes and number of proofs

::

threaded_engine(?nonvar) - zero_or_more

Errors

(none)

Examples

::

% check that the worker_1 engine exists: | ?- threaded_engine(worker_1).

% write the names of all existing engines: | ?- forall( threaded_engine(Engine), (writeq(Engine), nl) ).

.. seealso::

:ref:predicates_threaded_engine_create_3, :ref:predicates_threaded_engine_self_1, :ref:predicates_threaded_engine_destroy_1