MatchPy: A Pattern Matching Library

Abstract

Pattern matching is a powerful tool for symbolic computations, based on the well-defined theory of term rewriting systems. Application domains include algebraic expressions, abstract syntax trees, and XML and JSON data. Unfortunately, no lightweight implementation of pattern matching as general and flexible as Mathematica exists for Python [Pö16], [Hao14], [Sch14], [Jen15]. Therefore, we created the open source module MatchPy which offers similar pattern matching functionality in Python using a novel algorithm which finds matches for large pattern sets more efficiently by exploiting similarities between patterns.

Efficient Pattern Matching in Python

“…However, the employed discrimination nets come with a one-time construction cost which needs to be amortized to benefit from their speedup. In previous experiments [32], [33], when considering typical numbers of subjects for the respective application, many-to-one matching was always faster overall. Therefore, many-to-one matching is likely to result in a compelling speedup in practice.…”

“…multiprocessing or dask), the experiments do not cover this. We do not consider the singular setup time for many-to-one matching or code generation here, because previous experiments have shown that the setup time is easily amortized [32], [33].…”

MatchPy: Pattern Matching in Python

“…Unfortunately, no lightweight implementation of pattern matching as general and flexible as Mathematica exists for Python. The purpose of MatchPy Krebber, Barthels, and Bientinesi 2017a) is to provide this functionality in Python. While the pattern matching in SymPy (Meurer et al 2017) can work with associative/commutative functions, it does not support finding multiple matches, which is relevant in some applications.…”