The generic-random package

[ Tags: generics, library, mit, testing ] [ Propose Tags ]

Please see the README. Note: this package no longer exports Boltzmann samplers by default although they appear below. (Generic.Random.Data, Generic.Random.Boltzmann)

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Change log
Dependencies base (>=4.7 && <4.11), boltzmann-samplers (<=0.2), QuickCheck [details]
License MIT
Author Li-yao Xia
Category Generics, Testing
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Source repo head: git clone
Uploaded Mon Apr 10 15:27:49 UTC 2017 by lyxia
Updated Thu Jul 27 21:44:46 UTC 2017 by lyxia to revision 2   [What is this?]
Distributions LTSHaskell:, NixOS:, Stackage:, openSUSE:
Downloads 2881 total (117 in the last 30 days)
Rating 2.25 (votes: 2) [estimated by rule of succession]
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Status Docs available [build log]
Last success reported on 2017-04-10 [all 1 reports]
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Dependency on boltzmann-samplers for backwards compatibility.


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Maintainer's Corner

For package maintainers and hackage trustees

Readme for generic-random-

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Generic random generators Hackage Build Status

Say goodbye to Constructor <$> arbitrary <*> arbitrary <*> arbitrary-boilerplate.

    {-# LANGUAGE DeriveGeneric #-}

    import GHC.Generics ( Generic )
    import Test.QuickCheck
    import Generic.Random.Generic

    data Tree a = Leaf | Node (Tree a) a (Tree a)
      deriving (Show, Generic)

    instance Arbitrary a => Arbitrary (Tree a) where
      arbitrary = genericArbitrary' Z uniform

    -- Equivalent to
    -- > arbitrary =
    -- >   sized $ \n ->
    -- >     if n == 0 then
    -- >       return Leaf
    -- >     else
    -- >       oneof
    -- >         [ return Leaf
    -- >         , Node <$> arbitrary <*> arbitrary <*> arbitrary
    -- >         ]

    main = sample (arbitrary :: Gen (Tree ()))
  • User-specified distribution of constructors, with a compile-time check that weights have been specified for all constructors.
  • A simple (optional) strategy to ensure termination: Test.QuickCheck.Gen's size parameter decreases at every recursive genericArbitrary' call; when it reaches zero, sample directly from a finite set of finite values.