kleene

Kleene algebra

https://github.com/phadej/kleene

LTS Haskell 22.44:0.1@rev:8
Stackage Nightly 2026-05-16:0.2
Latest on Hackage:0.2

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BSD-3-Clause licensed and maintained by Oleg Grenrus
This version can be pinned in stack with:kleene-0.2@sha256:7d76731c450c797050bfe47cee5648b7b867ccfcb1e844b7e7278c31407e746e,2724

Module documentation for 0.2

Kleene algebra

Think: Regular expressions

Implements ideas from Regular-expression derivatives re-examined by Scott Owens, John Reppy and Aaron Turon https://doi.org/10.1017/S0956796808007090

Changes

0.2

  • Remove MChars constructor from Monad variant

0.1.1

  • Export Kleene.Functor.NonEmpty.few1
  • Export Kleene.RE.everything and Kleene.ERE.everything
  • Export Equivalent from Kleene

0.1

  • Drop superclasses from Kleene.
  • Rearrange classes. Introduce CharKleene, FiniteKleene.
  • Add ToLatin1 and ability to match on ByteString.
  • Add Derivate c (DFA c) instance.
  • Add toDot to output DFA to be rendered by graphviz.
  • Add fromRE :: RE c -> ERE c
  • Add nullableProof :: RE c -> Maybe (RE c) which returns non-nullable part of given regular expression.
  • Support/require lattices-2: RE is now a Lattice, M isn’t.