Parsley, like pyparsing and ZestyParser, uses the PEG algorithm, so each expression in the grammar rules works like a Python expression. In particular, alternatives are evaluated in order, unlike table-driven parsers such as yacc, bison or PLY.

Parsley is an implementation of OMeta, an object-oriented pattern-matching language developed by Alessandro Warth.

This package installs the library for Python 3.