.. _library_toychr:

toychr

This folder contains a Logtalk port of ToyCHR, a reference implementation of Constraint Handling Rules (CHR) available from:

::

https://www.comp.nus.edu.sg/~gregory/toychr/

The port is work in progress and includes significant modifications to the original code:

• Instead of compiling .chr files, it uses the term-expansion mechanism, by defining toychrdb as a hook object, to support writing rules inside objects and categories. As a consequence, the original chr_compile/1 is not available.
• The port is portable and should run on all supported backends. The port also includes examples ported from the SWI-Prolog CHR package examples and documentation. These examples are ported using the same license of the original code (BSD-2-Clause).

  For sample queries, please see the SCRIPT.txt file.

API documentation

Open the `../../docs/library_index.html#toychr <../../docs/library_index.html#toychr>`__ link in a web browser.

Loading

To load all entities in this port, load the loader.lgt file:

::

| ?- logtalk_load(toychr(loader)).

Testing

To test this port predicates, load the tester.lgt file:

::

| ?- logtalk_load(toychr(tester)).