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engines - emetas

This example requires support for both threads and coroutining. Currently it runs on ECLiPSe and SWI-Prolog. It should run also on XSB and YAP if and when these systems bugs with coroutining and/or threads get fixed.

This folder contains examples of using threaded engines for implementing meta-predicates. The best_of/3 meta-predicate example, is described in the paper:

@article{Tarau2000, author="Paul Tarau", title="Architecture and Implementation Aspects of the Lean Prolog System", url="http://www.cse.unt.edu/~tarau/research/LeanProlog/ArchitectureOfLeanProlog.pdf" }

Print Logtalk, Prolog backend, and kernel versions (if running as a notebook):

%versions

Load the example:

logtalk_load(emetas(loader)).

<!-- true. -->

Some clauses for a predicate used in the next queries:

assertz(a(2)), assertz(a(1)), assertz(a(4)), assertz(a(3)).

<!-- true. -->

Find the larger value from the values returned by a generator:

emetas::best_of(X, (>), a(X)).

<!-- X = 4. -->

Test the threaded engine implementation of the standard findall/3 meta-predicate:

emetas::find_all(X, a(X), List).

<!-- List = [2, 1, 4, 3]. -->

Test the threaded engine implementation of the find_at_most/4 meta-predicate:

emetas::find_at_most(3, X, a(X), Xs).

<!-- Xs = [2, 1, 4]. -->

emetas::find_at_most(7, X, a(X), Xs).

<!-- Xs = [2, 1, 4, 3]. -->