Ruly

Ruly is a simple, lightweight rule engine that can be used to define rules and prove statements using backward chaining. It attempts to be highly configurable, allowing callers of its functions to define callbacks in cases for conflict resolutions or derivations of new rules.

Installation

Ruly can be installed and used as a Python (>=3.6) package. It can be installed by calling:

pip install ruly

Usage

import ruly

knowledge_base = ruly.KnowledgeBase(
    'IF color = "red" THEN creature = "dragon"',
    'IF color = "grey" THEN creature = "rat"')
print(ruly.backward_chain(knowledge_base, 'creature', color='red'))
# prints dragon

For more examples and information on how to create new rules, solve conflicts, generate new rules on the fly during evaluations, etc., see the documentation.

Development environment

To set up the development environment, requirements must be installed either by calling setup.py or by installing them manually using pip and requirements.txt file. Also, ruly's build tool, doit needs to be installed. Supported tasks can be listed by calling:

doit list

NOTE: Ruly's development environment is using Python 3.12, but since Ruly does not require any runtime dependencies, the lowest supported version is Python 3.6. To test any new changes use the platform tests (doit plat_test) and update the minor version if backwards compatibility is broken. Additionally, there's CI support to test 3.7>, however 3.6 is not included in this because GH actions we