generic-random
Generic random generators for QuickCheck
http://github.com/lysxia/generic-random
LTS Haskell 22.37: | 1.5.0.1 |
Stackage Nightly 2024-10-07: | 1.5.0.1 |
Latest on Hackage: | 1.5.0.1 |
generic-random-1.5.0.1@sha256:70310b64747fa6cdbc53087c4cc3c3eba9614f4a4fba5d4651a67dea103d19e8,2618
Module documentation for 1.5.0.1
- Generic
Generic random generators
Generic random generators
to implement Arbitrary
instances for QuickCheck
Automating the arbitrary
boilerplate also ensures that when a type changes to
have more or fewer constructors, then the generator either fixes itself to
generate that new case (when using the uniform
distribution) or causes a
compilation error so you remember to fix it (when using an explicit
distribution).
This package also offers a simple (optional) strategy to ensure termination for
recursive types:
make Test.QuickCheck.Gen
’s size parameter decrease at every recursive call;
when it reaches zero, sample directly from a trivially terminating generator
given explicitly (genericArbitraryRec
and withBaseCase
) or implicitly
(genericArbitrary'
).
Example
{-# LANGUAGE DeriveGeneric #-}
import GHC.Generics (Generic)
import Test.QuickCheck
import Generic.Random
data Tree a = Leaf | Node (Tree a) a (Tree a)
deriving (Show, Generic)
instance Arbitrary a => Arbitrary (Tree a) where
arbitrary = genericArbitraryRec uniform `withBaseCase` return Leaf
-- Equivalent to
-- > arbitrary =
-- > sized $ \n ->
-- > if n == 0 then
-- > return Leaf
-- > else
-- > oneof
-- > [ return Leaf
-- > , resize (n `div` 3) $
-- > Node <$> arbitrary <*> arbitrary <*> arbitrary
-- > ]
main :: IO ()
main = sample (arbitrary :: Gen (Tree ()))
Related
-
The following two packages also derive random generators, but only with a uniform distribution of constructors:
- quickcheck-arbitrary-template (TH)
- generic-arbitrary (GHC Generics)
-
testing-feat: derive enumerations for algebraic data types, which can be turned into random generators (TH).
-
boltzmann-samplers: derive Boltzmann samplers (SYB).
Changes
Changelog
Latest version: https://github.com/Lysxia/generic-random/blob/master/changelog.md
1.5.1.0
- Support GHC 9.2
1.5.0.0
- Add newtypes for
DerivingVia
(thanks, blackheaven) - Drop compatibility with GHC 8.0 and 8.2
1.4.0.0
- Add option to use only coherent instances
- Export
SetSized
andSetUnsized
- Drop compatibility with GHC 7
1.3.0.1
- Fix small typos in documentation.
1.3.0.0
- Add
ConstrGen
(custom generators for fields specified by constructor name and index). - Stop requiring custom generators lists to be terminated by
:+ ()
, or to be lists at all. - Breaking minor change: when a record field has a different type than
a
FieldGen
custom generator for the same field name, this is now a compilation error. This was simply ignored before. - Miscellaneous documentation improvements in
Generic.Random
module.
1.2.0.0
-
Fix a bug where generators did not decrease the size parameter with single-field constructors
-
The sized generators now use a custom generator for lists. Use
genericArbitraryRecG ()
to disable that. See tutorial for more information. -
Lists of custom generators are now constructed using
(:+)
instead ofGenList
-
Rename
Field
toFieldGen
-
Add
Gen1
,Gen1_
(custom generators for unary type constructors) -
Add
listOf'
,listOf1'
,vectorOf'
-
Remove deprecated module
Generic.Random.Generic
1.1.0.2
- Improved performance
1.1.0.1
- Fix build for GHC<8
1.1.0.0
- Add option to specify custom generators for certain fields,
overriding Arbitrary instances
- Add
genericArbitraryG
,genericArbitraryUG
,genericArbitrarySingleG
,genericArbitraryRecG
- Add
- Add
GArbitrary
andGUniformWeight
synonyms - Deprecate
Generic.Random.Generic
- Remove
weights
from the external API
1.0.0.0
- Make the main module
Generic.Random
- Rework generic base case generation
- You can explicitly provide a trivial generator (e.g., returning a
nullary constructor) using
withBaseCase
- Generically derive
BaseCaseSearch
and letBaseCase
find small values, no depth parameter must be specified anymore
- You can explicitly provide a trivial generator (e.g., returning a
nullary constructor) using
- Add
genericArbitrarySingle
,genericArbitraryRec
,genericArbitraryU'
- Deprecate
weights
- Fixed bug with
genericArbitrary'
not dividing the size parameter
0.5.0.0
- Turn off dependency on boltzmann-samplers by default
- Add
genericArbitraryU
,genericArbitraryU0
andgenericArbitraryU1
- Compatible with GHC 7.8.4 and GHC 7.10.3
0.4.1.0
- Move Boltzmann sampler modules to another package: boltzmann-samplers
0.4.0.0
- Check well-formedness of constructor distributions at compile time.
- No longer support GHC 7.10.3 (the above feature relies on Generic information which does not exist before GHC 8)
0.3.0.0
- Support GHC 7.10.3
- Replace
TypeApplications
with ad-hoc data types ingenericArbitraryFrequency'
/genericArbitrary'