boltzmann-samplers: Uniform random generators

[ data, generic, library, mit, random ] [ Propose Tags ]
Dependencies ad, base (>=4.8 && <5), containers, hashable, hmatrix, ieee754, MonadRandom, mtl, QuickCheck, transformers, unordered‑containers, vector [details]
License MIT
Author Li-yao Xia
Revised Revision 1 made by lyxia at Sun Mar 5 22:43:09 UTC 2017
Category Data, Generic, Random
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Source repo head: git clone
Uploaded by lyxia at Sun Mar 5 20:25:38 UTC 2017
Distributions LTSHaskell:, NixOS:, openSUSE:
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Status Docs available [build log]
Last success reported on 2017-03-05 [all 1 reports]
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Random generators with a uniform distribution conditioned to a given size. See also testing-feat, which is currently a faster method with similar results.

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Boltzmann samplers Hackage Build Status


Define sized random generators for Data.Data generic types.

    {-# LANGUAGE DeriveDataTypeable #-}

    import Data.Data
    import Test.QuickCheck
    import Boltzmann.Data

    data Term = Lambda Int Term | App Term Term | Var Int
      deriving (Show, Data)

    instance Arbitrary Term where
      arbitrary = sized $ generatorPWith [positiveInts]

    positiveInts :: Alias Gen
    positiveInts =
      alias $ \() -> fmap getPositive arbitrary :: Gen Int

    main = sample (arbitrary :: Gen Term)
  • Objects of the same size (number of constructors) occur with the same probability (see Duchon et al., references below).
  • Implements rejection sampling and pointing.
  • Works with QuickCheck and MonadRandom, but also similar user-defined monads for randomness (just implement MonadRandomLike).
  • Can be tweaked somewhat with user defined generators.


An experimental interface to obtain Boltzmann samplers from an applicative specification of a combinatorial system.

No documentation (yet).