QuickCheck-2.10.0.1: Automatic testing of Haskell programs

Safe Haskell | Safe
Language | Haskell98

Test.QuickCheck.Arbitrary

Contents

- Arbitrary and CoArbitrary classes
  - Unary and Binary classes
  - Helper functions for implementing arbitrary
  - Generators for various kinds of character
  - Helper functions for implementing shrink
  - Helper functions for implementing coarbitrary
  - Generators which use arbitrary

Description

Type classes for random generation of values.

Synopsis

- class Arbitrary a where
- class CoArbitrary a where
- class Arbitrary1 f where
- arbitrary1 :: (Arbitrary1 f, Arbitrary a) => Gen (f a)
- shrink1 :: (Arbitrary1 f, Arbitrary a) => f a -> [f a]
- class Arbitrary2 f where
- arbitrary2 :: (Arbitrary2 f, Arbitrary a, Arbitrary b) => Gen (f a b)
- shrink2 :: (Arbitrary2 f, Arbitrary a, Arbitrary b) => f a b -> [f a b]
- arbitrarySizedIntegral :: Integral a => Gen a
- arbitrarySizedNatural :: Integral a => Gen a
- arbitraryBoundedIntegral :: (Bounded a, Integral a) => Gen a
- arbitrarySizedBoundedIntegral :: (Bounded a, Integral a) => Gen a
- arbitrarySizedFractional :: Fractional a => Gen a
- arbitraryBoundedRandom :: (Bounded a, Random a) => Gen a
- arbitraryBoundedEnum :: (Bounded a, Enum a) => Gen a
- arbitraryUnicodeChar :: Gen Char
- arbitraryASCIIChar :: Gen Char
- arbitraryPrintableChar :: Gen Char
- genericShrink :: (Generic a, RecursivelyShrink (Rep a), GSubterms (Rep a) a) => a -> [a]
- subterms :: (Generic a, GSubterms (Rep a) a) => a -> [a]
- recursivelyShrink :: (Generic a, RecursivelyShrink (Rep a)) => a -> [a]
- genericCoarbitrary :: (Generic a, GCoArbitrary (Rep a)) => a -> Gen b -> Gen b
- shrinkNothing :: a -> [a]
- shrinkList :: (a -> [a]) -> [a] -> [[a]]
- shrinkMap :: Arbitrary a => (a -> b) -> (b -> a) -> b -> [b]
- shrinkMapBy :: (a -> b) -> (b -> a) -> (a -> [a]) -> b -> [b]
- shrinkIntegral :: Integral a => a -> [a]
- shrinkRealFrac :: RealFrac a => a -> [a]
- coarbitraryIntegral :: Integral a => a -> Gen b -> Gen b
- coarbitraryReal :: Real a => a -> Gen b -> Gen b
- coarbitraryShow :: Show a => a -> Gen b -> Gen b
- coarbitraryEnum :: Enum a => a -> Gen b -> Gen b
- (><) :: (Gen a -> Gen a) -> (Gen a -> Gen a) -> Gen a -> Gen a
- vector :: Arbitrary a => Int -> Gen [a]
- orderedList :: (Ord a, Arbitrary a) => Gen [a]
- infiniteList :: Arbitrary a => Gen [a]

# Arbitrary and CoArbitrary classes

class Arbitrary a where #

Random generation and shrinking of values.

QuickCheck provides `Arbitrary` instances for most types in `base`, except those which incur extra dependencies. For a wider range of `Arbitrary` instances see the quickcheck-instances package.

Minimal complete definition

arbitrary

Methods

arbitrary :: Gen a #

A generator for values of the given type.

It is worth spending time thinking about what sort of test data you want - good generators are often the difference between finding bugs and not finding them. You can use `sample`, `label` and `classify` to check the quality of your test data.

There is no generic `arbitrary` implementation included because we don't know how to make a high-quality one. If you want one, consider using the testing-feat package.

The QuickCheck manual goes into detail on how to write good generators. Make sure to look at it, especially if your type is recursive!

shrink :: a -> [a] #

Produces a (possibly) empty list of all the possible immediate shrinks of the given value.

The default implementation returns the empty list, so will not try to shrink the value. If your data type has no special invariants, you can enable shrinking by defining `shrink = `genericShrink``, but by customising the behaviour of `shrink` you can often get simpler counterexamples.

Most implementations of `shrink` should try at least three things:

1. Shrink a term to any of its immediate subterms. You can use `subterms` to do this.
2. Recursively apply `shrink` to all immediate subterms. You can use `recursivelyShrink` to do this.
3. Type-specific shrinkings such as replacing a constructor by a simpler constructor.

For example, suppose we have the following implementation of binary trees:

    data Tree a = Nil | Branch a (Tree a) (Tree a)

We can then define `shrink` as follows:

    shrink Nil = []
    shrink (Branch x l r) =
      -- shrink Branch to Nil
      [Nil] ++
      -- shrink to subterms
      [l, r] ++
      -- recursively shrink subterms
      [Branch x' l' r' | (x', l', r') <- shrink (x, l, r)]

There are a couple of subtleties here:

- QuickCheck tries the shrinking candidates in the order they appear in the list, so we put more aggressive shrinking steps (such as replacing the whole tree by `Nil`) before smaller ones (such as recursively shrinking the subtrees).
- It is tempting to write the last line as `[Branch x' l' r' | x' <- shrink x, l' <- shrink l, r' <- shrink r]` but this is the wrong thing! It will force QuickCheck to shrink `x`, `l` and `r` in tandem, and shrinking will stop once one of the three is fully shrunk.

There is a fair bit of boilerplate in the code above. We can avoid it with the help of some generic functions. The function `genericShrink` tries shrinking a term to all of its subterms and, failing that, recursively shrinks the subterms. Using it, we can define `shrink` as:

    shrink x = shrinkToNil x ++ genericShrink x
      where
        shrinkToNil Nil = []
        shrinkToNil (Branch _ l r) = [Nil]

`genericShrink` is a combination of `subterms`, which shrinks a term to any of its subterms, and `recursivelyShrink`, which shrinks all subterms of a term. These may be useful if you need a bit more control over shrinking than `genericShrink` gives you.

A final gotcha: we cannot define `shrink` as simply ``shrink` x = Nil:`genericShrink` x` as this shrinks `Nil` to `Nil`, and shrinking will go into an infinite loop.

If all this leaves you bewildered, you might try ``shrink` = `genericShrink`` to begin with, after deriving `Generic` for your type. However, if your data type has any special invariants, you will need to check that `genericShrink` can't break those invariants.

Instances

Arbitrary Bool # |
Methods arbitrary :: Gen Bool # shrink :: Bool -> [Bool] #
Arbitrary Char # |
Methods arbitrary :: Gen Char # shrink :: Char -> [Char] #
Arbitrary Double # |
Methods arbitrary :: Gen Double # shrink :: Double -> [Double] #
Arbitrary Float # |
Methods arbitrary :: Gen Float # shrink :: Float -> [Float] #
Arbitrary Int # |
Methods arbitrary :: Gen Int # shrink :: Int -> [Int] #
Arbitrary Int8 # |
Methods arbitrary :: Gen Int8 # shrink :: Int8 -> [Int8] #
Arbitrary Int16 # |
Methods arbitrary :: Gen Int16 # shrink :: Int16 -> [Int16] #
Arbitrary Int32 # |
Methods arbitrary :: Gen Int32 # shrink :: Int32 -> [Int32] #
Arbitrary Int64 # |
Methods arbitrary :: Gen Int64 # shrink :: Int64 -> [Int64] #
Arbitrary Integer # |
Methods arbitrary :: Gen Integer # shrink :: Integer -> [Integer] #
Arbitrary Ordering # |
Methods arbitrary :: Gen Ordering # shrink :: Ordering -> [Ordering] #
Arbitrary Word # |
Methods arbitrary :: Gen Word # shrink :: Word -> [Word] #
Arbitrary Word8 # |
Methods arbitrary :: Gen Word8 # shrink :: Word8 -> [Word8] #
Arbitrary Word16 # |
Methods arbitrary :: Gen Word16 # shrink :: Word16 -> [Word16] #
Arbitrary Word32 # |
Methods arbitrary :: Gen Word32 # shrink :: Word32 -> [Word32] #
Arbitrary Word64 # |
Methods arbitrary :: Gen Word64 # shrink :: Word64 -> [Word64] #
Arbitrary () # |
Methods arbitrary :: Gen () # shrink :: () -> [()] #
Arbitrary Version # | Generates `Version` with non-empty non-negative `versionBranch`, and empty `versionTags`
Methods arbitrary :: Gen Version # shrink :: Version -> [Version] #
Arbitrary ExitCode # |
Methods arbitrary :: Gen ExitCode # shrink :: ExitCode -> [ExitCode] #
Arbitrary CChar # |
Methods arbitrary :: Gen CChar # shrink :: CChar -> [CChar] #
Arbitrary CSChar # |
Methods arbitrary :: Gen CSChar # shrink :: CSChar -> [CSChar] #
Arbitrary CUChar # |
Methods arbitrary :: Gen CUChar # shrink :: CUChar -> [CUChar] #
Arbitrary CShort # |
Methods arbitrary :: Gen CShort # shrink :: CShort -> [CShort] #
Arbitrary CUShort # |
Methods arbitrary :: Gen CUShort # shrink :: CUShort -> [CUShort] #
Arbitrary CInt # |
Methods arbitrary :: Gen CInt # shrink :: CInt -> [CInt] #
Arbitrary CUInt # |
Methods arbitrary :: Gen CUInt # shrink :: CUInt -> [CUInt] #
Arbitrary CLong # |
Methods arbitrary :: Gen CLong # shrink :: CLong -> [CLong] #
Arbitrary CULong # |
Methods arbitrary :: Gen CULong # shrink :: CULong -> [CULong] #
Arbitrary CLLong # |
Methods arbitrary :: Gen CLLong # shrink :: CLLong -> [CLLong] #
Arbitrary CULLong # |
Methods arbitrary :: Gen CULLong # shrink :: CULLong -> [CULLong] #
Arbitrary CFloat # |
Methods arbitrary :: Gen CFloat # shrink :: CFloat -> [CFloat] #
Arbitrary CDouble # |
Methods arbitrary :: Gen CDouble # shrink :: CDouble -> [CDouble] #
Arbitrary CPtrdiff # |
Methods arbitrary :: Gen CPtrdiff # shrink :: CPtrdiff -> [CPtrdiff] #
Arbitrary CSize # |
Methods arbitrary :: Gen CSize # shrink :: CSize -> [CSize] #
Arbitrary CWchar # |
Methods arbitrary :: Gen CWchar # shrink :: CWchar -> [CWchar] #
Arbitrary CSigAtomic # |
Methods arbitrary :: Gen CSigAtomic # shrink :: CSigAtomic -> [CSigAtomic] #
Arbitrary CClock # |
Methods arbitrary :: Gen CClock # shrink :: CClock -> [CClock] #
Arbitrary CTime # |
Methods arbitrary :: Gen CTime # shrink :: CTime -> [CTime] #
Arbitrary CUSeconds # |
Methods arbitrary :: Gen CUSeconds # shrink :: CUSeconds -> [CUSeconds] #
Arbitrary CSUSeconds # |
Methods arbitrary :: Gen CSUSeconds # shrink :: CSUSeconds -> [CSUSeconds] #
Arbitrary CIntPtr # |
Methods arbitrary :: Gen CIntPtr # shrink :: CIntPtr -> [CIntPtr] #
Arbitrary CUIntPtr # |
Methods arbitrary :: Gen CUIntPtr # shrink :: CUIntPtr -> [CUIntPtr] #
Arbitrary CIntMax # |
Methods arbitrary :: Gen CIntMax # shrink :: CIntMax -> [CIntMax] #
Arbitrary CUIntMax # |
Methods arbitrary :: Gen CUIntMax # shrink :: CUIntMax -> [CUIntMax] #
Arbitrary All # |
Methods arbitrary :: Gen All # shrink :: All -> [All] #
Arbitrary Any # |
Methods arbitrary :: Gen Any # shrink :: Any -> [Any] #
Arbitrary IntSet # |
Methods arbitrary :: Gen IntSet # shrink :: IntSet -> [IntSet] #
Arbitrary QCGen # |
Methods arbitrary :: Gen QCGen # shrink :: QCGen -> [QCGen] #
Arbitrary PrintableString # |
Methods arbitrary :: Gen PrintableString # shrink :: PrintableString -> [PrintableString] #
Arbitrary UnicodeString # |
Methods arbitrary :: Gen UnicodeString # shrink :: UnicodeString -> [UnicodeString] #
Arbitrary ASCIIString # |
Methods arbitrary :: Gen ASCIIString # shrink :: ASCIIString -> [ASCIIString] #
Arbitrary OrdC # |
Methods arbitrary :: Gen OrdC # shrink :: OrdC -> [OrdC] #
Arbitrary OrdB # |
Methods arbitrary :: Gen OrdB # shrink :: OrdB -> [OrdB] #
Arbitrary OrdA # |
Methods arbitrary :: Gen OrdA # shrink :: OrdA -> [OrdA] #
Arbitrary C # |
Methods arbitrary :: Gen C # shrink :: C -> [C] #
Arbitrary B # |
Methods arbitrary :: Gen B # shrink :: B -> [B] #
Arbitrary A # |
Methods arbitrary :: Gen A # shrink :: A -> [A] #
Arbitrary a => Arbitrary [a] # |
Methods arbitrary :: Gen [a] # shrink :: [a] -> [[a]] #
Arbitrary a => Arbitrary (Maybe a) # |
Methods arbitrary :: Gen (Maybe a) # shrink :: Maybe a -> [Maybe a] #
Integral a => Arbitrary (Ratio a) # |
Methods arbitrary :: Gen (Ratio a) # shrink :: Ratio a -> [Ratio a] #
Arbitrary a => Arbitrary (Identity a) # |
Methods arbitrary :: Gen (Identity a) # shrink :: Identity a -> [Identity a] #
HasResolution a => Arbitrary (Fixed a) # |
Methods arbitrary :: Gen (Fixed a) # shrink :: Fixed a -> [Fixed a] #
(RealFloat a, Arbitrary a) => Arbitrary (Complex a) # |
Methods arbitrary :: Gen (Complex a) # shrink :: Complex a -> [Complex a] #
Arbitrary a => Arbitrary (ZipList a) # |
Methods arbitrary :: Gen (ZipList a) # shrink :: ZipList a -> [ZipList a] #
Arbitrary a => Arbitrary (Dual a) # |
Methods arbitrary :: Gen (Dual a) # shrink :: Dual a -> [Dual a] #
(Arbitrary a, CoArbitrary a) => Arbitrary (Endo a) # |
Methods arbitrary :: Gen (Endo a) # shrink :: Endo a -> [Endo a] #
Arbitrary a => Arbitrary (Sum a) # |
Methods arbitrary :: Gen (Sum a) # shrink :: Sum a -> [Sum a] #
Arbitrary a => Arbitrary (Product a) # |
Methods arbitrary :: Gen (Product a) # shrink :: Product a -> [Product a] #
Arbitrary a => Arbitrary (First a) # |
Methods arbitrary :: Gen (First a) # shrink :: First a -> [First a] #
Arbitrary a => Arbitrary (Last a) # |
Methods arbitrary :: Gen (Last a) # shrink :: Last a -> [Last a] #
Arbitrary a => Arbitrary (IntMap a) # |
Methods arbitrary :: Gen (IntMap a) # shrink :: IntMap a -> [IntMap a] #
Arbitrary a => Arbitrary (Seq a) # |
Methods arbitrary :: Gen (Seq a) # shrink :: Seq a -> [Seq a] #
(Ord a, Arbitrary a) => Arbitrary (Set a) # |
Methods arbitrary :: Gen (Set a) # shrink :: Set a -> [Set a] #
Arbitrary a => Arbitrary (Smart a) # |
Methods arbitrary :: Gen (Smart a) # shrink :: Smart a -> [Smart a] #
Arbitrary a => Arbitrary (Shrink2 a) # |
Methods arbitrary :: Gen (Shrink2 a) # shrink :: Shrink2 a -> [Shrink2 a] #
Integral a => Arbitrary (Small a) # |
Methods arbitrary :: Gen (Small a) # shrink :: Small a -> [Small a] #
(Integral a, Bounded a) => Arbitrary (Large a) # |
Methods arbitrary :: Gen (Large a) # shrink :: Large a -> [Large a] #
(Num a, Ord a, Arbitrary a) => Arbitrary (NonNegative a) # |
Methods arbitrary :: Gen (NonNegative a) # shrink :: NonNegative a -> [NonNegative a] #
(Num a, Eq a, Arbitrary a) => Arbitrary (NonZero a) # |
Methods arbitrary :: Gen (NonZero a) # shrink :: NonZero a -> [NonZero a] #
(Num a, Ord a, Arbitrary a) => Arbitrary (Positive a) # |
Methods arbitrary :: Gen (Positive a) # shrink :: Positive a -> [Positive a] #
Arbitrary a => Arbitrary (NonEmptyList a) # |
Methods arbitrary :: Gen (NonEmptyList a) # shrink :: NonEmptyList a -> [NonEmptyList a] #
(Ord a, Arbitrary a) => Arbitrary (OrderedList a) # |
Methods arbitrary :: Gen (OrderedList a) # shrink :: OrderedList a -> [OrderedList a] #
Arbitrary a => Arbitrary (Fixed a) # |
Methods arbitrary :: Gen (Fixed a) # shrink :: Fixed a -> [Fixed a] #
Arbitrary a => Arbitrary (Blind a) # |
Methods arbitrary :: Gen (Blind a) # shrink :: Blind a -> [Blind a] #
(CoArbitrary a, Arbitrary b) => Arbitrary (a -> b) # |
Methods arbitrary :: Gen (a -> b) # shrink :: (a -> b) -> [a -> b] #
(Arbitrary a, Arbitrary b) => Arbitrary (Either a b) # |
Methods arbitrary :: Gen (Either a b) # shrink :: Either a b -> [Either a b] #
(Arbitrary a, Arbitrary b) => Arbitrary (a, b) # |
Methods arbitrary :: Gen (a, b) # shrink :: (a, b) -> [(a, b)] #
Arbitrary (m a) => Arbitrary (WrappedMonad m a) # |
Methods arbitrary :: Gen (WrappedMonad m a) # shrink :: WrappedMonad m a -> [WrappedMonad m a] #
(Ord k, Arbitrary k, Arbitrary v) => Arbitrary (Map k v) # |
Methods arbitrary :: Gen (Map k v) # shrink :: Map k v -> [Map k v] #
(Arbitrary a, ShrinkState s a) => Arbitrary (Shrinking s a) # |
Methods arbitrary :: Gen (Shrinking s a) # shrink :: Shrinking s a -> [Shrinking s a] #
(Function a, CoArbitrary a, Arbitrary b) => Arbitrary (Fun a b) # |
Methods arbitrary :: Gen (Fun a b) # shrink :: Fun a b -> [Fun a b] #
(Function a, CoArbitrary a, Arbitrary b) => Arbitrary ((:->) a b) # |
Methods arbitrary :: Gen (a :-> b) # shrink :: (a :-> b) -> [a :-> b] #
(Arbitrary a, Arbitrary b, Arbitrary c) => Arbitrary (a, b, c) # |
Methods arbitrary :: Gen (a, b, c) # shrink :: (a, b, c) -> [(a, b, c)] #
Arbitrary (a b c) => Arbitrary (WrappedArrow a b c) # |
Methods arbitrary :: Gen (WrappedArrow a b c) # shrink :: WrappedArrow a b c -> [WrappedArrow a b c] #
Arbitrary a => Arbitrary (Const k a b) # |
Methods arbitrary :: Gen (Const k a b) # shrink :: Const k a b -> [Const k a b] #
Arbitrary (f a) => Arbitrary (Alt k f a) # |
Methods arbitrary :: Gen (Alt k f a) # shrink :: Alt k f a -> [Alt k f a] #
Arbitrary a => Arbitrary (Constant k a b) # |
Methods arbitrary :: Gen (Constant k a b) # shrink :: Constant k a b -> [Constant k a b] #
(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d) => Arbitrary (a, b, c, d) # |
Methods arbitrary :: Gen (a, b, c, d) # shrink :: (a, b, c, d) -> [(a, b, c, d)] #
(Arbitrary1 f, Arbitrary1 g, Arbitrary a) => Arbitrary (Product * f g a) # |
Methods arbitrary :: Gen (Product * f g a) # shrink :: Product * f g a -> [Product * f g a] #
(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d, Arbitrary e) => Arbitrary (a, b, c, d, e) # |
Methods arbitrary :: Gen (a, b, c, d, e) # shrink :: (a, b, c, d, e) -> [(a, b, c, d, e)] #
(Arbitrary1 f, Arbitrary1 g, Arbitrary a) => Arbitrary (Compose * * f g a) # |
Methods arbitrary :: Gen (Compose * * f g a) # shrink :: Compose * * f g a -> [Compose * * f g a] #
(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d, Arbitrary e, Arbitrary f) => Arbitrary (a, b, c, d, e, f) # |
Methods arbitrary :: Gen (a, b, c, d, e, f) # shrink :: (a, b, c, d, e, f) -> [(a, b, c, d, e, f)] #
(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d, Arbitrary e, Arbitrary f, Arbitrary g) => Arbitrary (a, b, c, d, e, f, g) # |
Methods arbitrary :: Gen (a, b, c, d, e, f, g) # shrink :: (a, b, c, d, e, f, g) -> [(a, b, c, d, e, f, g)] #
(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d, Arbitrary e, Arbitrary f, Arbitrary g, Arbitrary h) => Arbitrary (a, b, c, d, e, f, g, h) # |
Methods arbitrary :: Gen (a, b, c, d, e, f, g, h) # shrink :: (a, b, c, d, e, f, g, h) -> [(a, b, c, d, e, f, g, h)] #
(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d, Arbitrary e, Arbitrary f, Arbitrary g, Arbitrary h, Arbitrary i) => Arbitrary (a, b, c, d, e, f, g, h, i) # |
Methods arbitrary :: Gen (a, b, c, d, e, f, g, h, i) # shrink :: (a, b, c, d, e, f, g, h, i) -> [(a, b, c, d, e, f, g, h, i)] #
(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d, Arbitrary e, Arbitrary f, Arbitrary g, Arbitrary h, Arbitrary i, Arbitrary j) => Arbitrary (a, b, c, d, e, f, g, h, i, j) # |
Methods arbitrary :: Gen (a, b, c, d, e, f, g, h, i, j) # shrink :: (a, b, c, d, e, f, g, h, i, j) -> [(a, b, c, d, e, f, g, h, i, j)] #

class CoArbitrary a where #

Used for random generation of functions.

If you are using a recent GHC, there is a default definition of `coarbitrary` using `genericCoarbitrary`, so if your type has a `Generic` instance it's enough to say

    instance CoArbitrary MyType

You should only use `genericCoarbitrary` for data types where equality is structural, i.e. if you can't have two different representations of the same value. An example where it's not safe is sets implemented using binary search trees: the same set can be represented as several different trees. Here you would have to explicitly define `coarbitrary s = coarbitrary (toList s)`.

Methods

coarbitrary :: a -> Gen b -> Gen b #

Used to generate a function of type `a -> b`. The first argument is a value, the second a generator. You should use `variant` to perturb the random generator; the goal is that different values for the first argument will lead to different calls to `variant`. An example will help:

    instance CoArbitrary a => CoArbitrary [a] where
      coarbitrary []     = variant 0
      coarbitrary (x:xs) = variant 1 . coarbitrary (x,xs)

coarbitrary :: (Generic a, GCoArbitrary (Rep a)) => a -> Gen b -> Gen b #

Used to generate a function of type `a -> b`. The first argument is a value, the second a generator. You should use `variant` to perturb the random generator; the goal is that different values for the first argument will lead to different calls to `variant`. An example will help:

    instance CoArbitrary a => CoArbitrary [a] where
      coarbitrary []     = variant 0
      coarbitrary (x:xs) = variant 1 . coarbitrary (x,xs)

Instances

CoArbitrary Bool # |
Methods coarbitrary :: Bool -> Gen b -> Gen b #
CoArbitrary Char # |
Methods coarbitrary :: Char -> Gen b -> Gen b #
CoArbitrary Double # |
Methods coarbitrary :: Double -> Gen b -> Gen b #
CoArbitrary Float # |
Methods coarbitrary :: Float -> Gen b -> Gen b #
CoArbitrary Int # |
Methods coarbitrary :: Int -> Gen b -> Gen b #
CoArbitrary Int8 # |
Methods coarbitrary :: Int8 -> Gen b -> Gen b #
CoArbitrary Int16 # |
Methods coarbitrary :: Int16 -> Gen b -> Gen b #
CoArbitrary Int32 # |
Methods coarbitrary :: Int32 -> Gen b -> Gen b #
CoArbitrary Int64 # |
Methods coarbitrary :: Int64 -> Gen b -> Gen b #
CoArbitrary Integer # |
Methods coarbitrary :: Integer -> Gen b -> Gen b #
CoArbitrary Ordering # |
Methods coarbitrary :: Ordering -> Gen b -> Gen b #
CoArbitrary Word # |
Methods coarbitrary :: Word -> Gen b -> Gen b #
CoArbitrary Word8 # |
Methods coarbitrary :: Word8 -> Gen b -> Gen b #
CoArbitrary Word16 # |
Methods coarbitrary :: Word16 -> Gen b -> Gen b #
CoArbitrary Word32 # |
Methods coarbitrary :: Word32 -> Gen b -> Gen b #
CoArbitrary Word64 # |
Methods coarbitrary :: Word64 -> Gen b -> Gen b #
CoArbitrary () # |
Methods coarbitrary :: () -> Gen b -> Gen b #
CoArbitrary Version # |
Methods coarbitrary :: Version -> Gen b -> Gen b #
CoArbitrary All # |
Methods coarbitrary :: All -> Gen b -> Gen b #
CoArbitrary Any # |
Methods coarbitrary :: Any -> Gen b -> Gen b #
CoArbitrary IntSet # |
Methods coarbitrary :: IntSet -> Gen b -> Gen b #
CoArbitrary OrdC # |
Methods coarbitrary :: OrdC -> Gen b -> Gen b #
CoArbitrary OrdB # |
Methods coarbitrary :: OrdB -> Gen b -> Gen b #
CoArbitrary OrdA # |
Methods coarbitrary :: OrdA -> Gen b -> Gen b #
CoArbitrary C # |
Methods coarbitrary :: C -> Gen b -> Gen b #
CoArbitrary B # |
Methods coarbitrary :: B -> Gen b -> Gen b #
CoArbitrary A # |
Methods coarbitrary :: A -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary [a] # |
Methods coarbitrary :: [a] -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Maybe a) # |
Methods coarbitrary :: Maybe a -> Gen b -> Gen b #
(Integral a, CoArbitrary a) => CoArbitrary (Ratio a) # |
Methods coarbitrary :: Ratio a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Identity a) # |
Methods coarbitrary :: Identity a -> Gen b -> Gen b #
HasResolution a => CoArbitrary (Fixed a) # |
Methods coarbitrary :: Fixed a -> Gen b -> Gen b #
(RealFloat a, CoArbitrary a) => CoArbitrary (Complex a) # |
Methods coarbitrary :: Complex a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (ZipList a) # |
Methods coarbitrary :: ZipList a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Dual a) # |
Methods coarbitrary :: Dual a -> Gen b -> Gen b #
(Arbitrary a, CoArbitrary a) => CoArbitrary (Endo a) # |
Methods coarbitrary :: Endo a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Sum a) # |
Methods coarbitrary :: Sum a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Product a) # |
Methods coarbitrary :: Product a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (First a) # |
Methods coarbitrary :: First a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Last a) # |
Methods coarbitrary :: Last a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (IntMap a) # |
Methods coarbitrary :: IntMap a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Seq a) # |
Methods coarbitrary :: Seq a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Set a) # |
Methods coarbitrary :: Set a -> Gen b -> Gen b #
(Arbitrary a, CoArbitrary b) => CoArbitrary (a -> b) # |
Methods coarbitrary :: (a -> b) -> Gen b -> Gen b #
(CoArbitrary a, CoArbitrary b) => CoArbitrary (Either a b) # |
Methods coarbitrary :: Either a b -> Gen b -> Gen b #
(CoArbitrary a, CoArbitrary b) => CoArbitrary (a, b) # |
Methods coarbitrary :: (a, b) -> Gen b -> Gen b #
(CoArbitrary k, CoArbitrary v) => CoArbitrary (Map k v) # |
Methods coarbitrary :: Map k v -> Gen b -> Gen b #
(CoArbitrary a, CoArbitrary b, CoArbitrary c) => CoArbitrary (a, b, c) # |
Methods coarbitrary :: (a, b, c) -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Const k a b) # |
Methods coarbitrary :: Const k a b -> Gen b -> Gen b #
CoArbitrary (f a) => CoArbitrary (Alt k f a) # |
Methods coarbitrary :: Alt k f a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Constant k a b) # |
Methods coarbitrary :: Constant k a b -> Gen b -> Gen b #
(CoArbitrary a, CoArbitrary b, CoArbitrary c, CoArbitrary d) => CoArbitrary (a, b, c, d) # |
Methods coarbitrary :: (a, b, c, d) -> Gen b -> Gen b #
(CoArbitrary a, CoArbitrary b, CoArbitrary c, CoArbitrary d, CoArbitrary e) => CoArbitrary (a, b, c, d, e) # |
Methods coarbitrary :: (a, b, c, d, e) -> Gen b -> Gen b #

## Unary and Binary classes

class Arbitrary1 f where #

Lifting of the `Arbitrary` class to unary type constructors.

Minimal complete definition

liftArbitrary

Methods

liftArbitrary :: Gen a -> Gen (f a) #

liftShrink :: (a -> [a]) -> f a -> [f a] #

Instances

Arbitrary1 [] # |
Methods liftArbitrary :: Gen a -> Gen [a] # liftShrink :: (a -> [a]) -> [a] -> [[a]] #
Arbitrary1 Maybe # |
Methods liftArbitrary :: Gen a -> Gen (Maybe a) # liftShrink :: (a -> [a]) -> Maybe a -> [Maybe a] #
Arbitrary1 Identity # |
Methods liftArbitrary :: Gen a -> Gen (Identity a) # liftShrink :: (a -> [a]) -> Identity a -> [Identity a] #
Arbitrary1 ZipList # |
Methods liftArbitrary :: Gen a -> Gen (ZipList a) # liftShrink :: (a -> [a]) -> ZipList a -> [ZipList a] #
Arbitrary1 IntMap # |
Methods liftArbitrary :: Gen a -> Gen (IntMap a) # liftShrink :: (a -> [a]) -> IntMap a -> [IntMap a] #
Arbitrary1 Seq # |
Methods liftArbitrary :: Gen a -> Gen (Seq a) # liftShrink :: (a -> [a]) -> Seq a -> [Seq a] #
CoArbitrary a => Arbitrary1 ((->) a) # |
Methods liftArbitrary :: Gen a -> Gen (a -> a) # liftShrink :: (a -> [a]) -> (a -> a) -> [a -> a] #
Arbitrary a => Arbitrary1 (Either a) # |
Methods liftArbitrary :: Gen a -> Gen (Either a a) # liftShrink :: (a -> [a]) -> Either a a -> [Either a a] #
Arbitrary a => Arbitrary1 ((,) a) # |
Methods liftArbitrary :: Gen a -> Gen (a, a) # liftShrink :: (a -> [a]) -> (a, a) -> [(a, a)] #
(Ord k, Arbitrary k) => Arbitrary1 (Map k) # |
Methods liftArbitrary :: Gen a -> Gen (Map k a) # liftShrink :: (a -> [a]) -> Map k a -> [Map k a] #
Arbitrary a => Arbitrary1 (Const * a) # |
Methods liftArbitrary :: Gen a -> Gen (Const * a a) # liftShrink :: (a -> [a]) -> Const * a a -> [Const * a a] #
Arbitrary a => Arbitrary1 (Constant * a) # |
Methods liftArbitrary :: Gen a -> Gen (Constant * a a) # liftShrink :: (a -> [a]) -> Constant * a a -> [Constant * a a] #
(Arbitrary1 f, Arbitrary1 g) => Arbitrary1 (Product * f g) # |
Methods liftArbitrary :: Gen a -> Gen (Product * f g a) # liftShrink :: (a -> [a]) -> Product * f g a -> [Product * f g a] #
(Arbitrary1 f, Arbitrary1 g) => Arbitrary1 (Compose * * f g) # |
Methods liftArbitrary :: Gen a -> Gen (Compose * * f g a) # liftShrink :: (a -> [a]) -> Compose * * f g a -> [Compose * * f g a] #

arbitrary1 :: (Arbitrary1 f, Arbitrary a) => Gen (f a) #

shrink1 :: (Arbitrary1 f, Arbitrary a) => f a -> [f a] #

class Arbitrary2 f where #

Lifting of the `Arbitrary` class to binary type constructors.

Minimal complete definition

liftArbitrary2

Methods

liftArbitrary2 :: Gen a -> Gen b -> Gen (f a b) #

liftShrink2 :: (a -> [a]) -> (b -> [b]) -> f a b -> [f a b] #

Instances

Arbitrary2 Either # |
Methods liftArbitrary2 :: Gen a -> Gen b -> Gen (Either a b) # liftShrink2 :: (a -> [a]) -> (b -> [b]) -> Either a b -> [Either a b] #
Arbitrary2 (,) # |
Methods liftArbitrary2 :: Gen a -> Gen b -> Gen (a, b) # liftShrink2 :: (a -> [a]) -> (b -> [b]) -> (a, b) -> [(a, b)] #
Arbitrary2 (Const *) # |
Methods liftArbitrary2 :: Gen a -> Gen b -> Gen (Const * a b) # liftShrink2 :: (a -> [a]) -> (b -> [b]) -> Const * a b -> [Const * a b] #
Arbitrary2 (Constant *) # |
Methods liftArbitrary2 :: Gen a -> Gen b -> Gen (Constant * a b) # liftShrink2 :: (a -> [a]) -> (b -> [b]) -> Constant * a b -> [Constant * a b] #

arbitrary2 :: (Arbitrary2 f, Arbitrary a, Arbitrary b) => Gen (f a b) #

shrink2 :: (Arbitrary2 f, Arbitrary a, Arbitrary b) => f a b -> [f a b] #

## Helper functions for implementing arbitrary

arbitrarySizedIntegral :: Integral a => Gen a #

Generates an integral number. The number can be positive or negative and its maximum absolute value depends on the size parameter.

arbitrarySizedNatural :: Integral a => Gen a #

Generates a natural number. The number's maximum value depends on the size parameter.

arbitraryBoundedIntegral :: (Bounded a, Integral a) => Gen a #

Generates an integral number. The number is chosen uniformly from the entire range of the type. You may want to use `arbitrarySizedBoundedIntegral` instead.

arbitrarySizedBoundedIntegral :: (Bounded a, Integral a) => Gen a #

Generates an integral number from a bounded domain. The number is chosen from the entire range of the type, but small numbers are generated more often than big numbers. Inspired by demands from Phil Wadler.

arbitrarySizedFractional :: Fractional a => Gen a #

Generates a fractional number. The number can be positive or negative and its maximum absolute value depends on the size parameter.

arbitraryBoundedRandom :: (Bounded a, Random a) => Gen a #

Generates an element of a bounded type. The element is chosen from the entire range of the type.

arbitraryBoundedEnum :: (Bounded a, Enum a) => Gen a #

Generates an element of a bounded enumeration.

## Generators for various kinds of character

arbitraryUnicodeChar :: Gen Char #

Generates any Unicode character (but not a surrogate)

arbitraryASCIIChar :: Gen Char #

Generates a random ASCII character (0-127).

arbitraryPrintableChar :: Gen Char #

Generates a printable Unicode character.

## Helper functions for implementing shrink

genericShrink :: (Generic a, RecursivelyShrink (Rep a), GSubterms (Rep a) a) => a -> [a] #

Shrink a term to any of its immediate subterms, and also recursively shrink all subterms.

subterms :: (Generic a, GSubterms (Rep a) a) => a -> [a] #

All immediate subterms of a term.

recursivelyShrink :: (Generic a, RecursivelyShrink (Rep a)) => a -> [a] #

Recursively shrink all immediate subterms.

genericCoarbitrary :: (Generic a, GCoArbitrary (Rep a)) => a -> Gen b -> Gen b #

Generic CoArbitrary implementation.

shrinkNothing :: a -> [a] #

Returns no shrinking alternatives.

shrinkList :: (a -> [a]) -> [a] -> [[a]] #

Shrink a list of values given a shrinking function for individual values.

shrinkMap :: Arbitrary a => (a -> b) -> (b -> a) -> b -> [b] #

Map a shrink function to another domain. This is handy if your data type has special invariants, but is almost isomorphic to some other type.

    shrinkOrderedList :: (Ord a, Arbitrary a) => [a] -> [[a]]
    shrinkOrderedList = shrinkMap sort id

    shrinkSet :: (Ord a, Arbitrary a) => Set a -> Set [a]
    shrinkSet = shrinkMap fromList toList

shrinkMapBy :: (a -> b) -> (b -> a) -> (a -> [a]) -> b -> [b] #

Non-overloaded version of `shrinkMap`.

shrinkIntegral :: Integral a => a -> [a] #

Shrink an integral number.

shrinkRealFrac :: RealFrac a => a -> [a] #

Shrink a fraction.

## Helper functions for implementing coarbitrary

coarbitraryIntegral :: Integral a => a -> Gen b -> Gen b #

A `coarbitrary` implementation for integral numbers.

coarbitraryReal :: Real a => a -> Gen b -> Gen b #

A `coarbitrary` implementation for real numbers.

coarbitraryShow :: Show a => a -> Gen b -> Gen b #

`coarbitrary` helper for lazy people :-).

coarbitraryEnum :: Enum a => a -> Gen b -> Gen b #

A `coarbitrary` implementation for enums.

(><) :: (Gen a -> Gen a) -> (Gen a -> Gen a) -> Gen a -> Gen a #

Deprecated: Use ordinary function composition instead

Combine two generator perturbing functions, for example the results of calls to `variant` or `coarbitrary`.

## Generators which use arbitrary

vector :: Arbitrary a => Int -> Gen [a] #

Generates a list of a given length.

orderedList :: (Ord a, Arbitrary a) => Gen [a] #

Generates an ordered list.

infiniteList :: Arbitrary a => Gen [a] #

Generates an infinite list.