HsSPE is a Haskell library for implementing SPE-style rule-based phonologies. It is designed to be easy to extend, both in terms of feature systems/segment definitions and in terms of rule parsers. It includes the following components: * Data.Phonology.Features - a library for parsing, serializing, and manipulating matrices of binary features (underspecification allowed) and for parsing IPA strings into lists of segment/feature matrix pairs. * Data.Phonology.RuleParsers - a library for parsing string representations of phonological rules. * Data.Phonology.Rules - a library defining phonological rules and functions for their application to representations.