QuickCheck-2.14.3: Automatic testing of Haskell programs

Safe Haskell | Trustworthy
Language | Haskell2010

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.

Note: the contents of this module are re-exported by Test.QuickCheck. You do not need to import it directly.

Synopsis

- class Arbitrary a where
  - arbitrary :: Gen a
  - shrink :: a -> [a]
- class CoArbitrary a where
  - coarbitrary :: a -> Gen b -> Gen b
- class Arbitrary1 f where
  - liftArbitrary :: Gen a -> Gen (f a)
  - liftShrink :: (a -> [a]) -> f a -> [f a]
- arbitrary1 :: (Arbitrary1 f, Arbitrary a) => Gen (f a)
- shrink1 :: (Arbitrary1 f, Arbitrary a) => f a -> [f a]
- class Arbitrary2 f where
  - liftArbitrary2 :: Gen a -> Gen b -> Gen (f a b)
  - liftShrink2 :: (a -> [a]) -> (b -> [b]) -> f a b -> [f 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]
- applyArbitrary2 :: (Arbitrary a, Arbitrary b) => (a -> b -> r) -> Gen r
- applyArbitrary3 :: (Arbitrary a, Arbitrary b, Arbitrary c) => (a -> b -> c -> r) -> Gen r
- applyArbitrary4 :: (Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d) => (a -> b -> c -> d -> r) -> Gen r
- 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
- class RecursivelyShrink f
- class GSubterms f a
- 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]
- shrinkBoundedEnum :: (Bounded a, Enum a, Eq a) => a -> [a]
- shrinkDecimal :: 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 or generic-random packages.

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

Instances details

Arbitrary ASCIIString # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen ASCIIString # shrink :: ASCIIString -> [ASCIIString] #
Arbitrary PrintableString # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen PrintableString # shrink :: PrintableString -> [PrintableString] #
Arbitrary UnicodeString # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen UnicodeString # shrink :: UnicodeString -> [UnicodeString] #
Arbitrary A # |
Instance details Defined in Test.QuickCheck.Poly Methods arbitrary :: Gen A # shrink :: A -> [A] #
Arbitrary B # |
Instance details Defined in Test.QuickCheck.Poly Methods arbitrary :: Gen B # shrink :: B -> [B] #
Arbitrary C # |
Instance details Defined in Test.QuickCheck.Poly Methods arbitrary :: Gen C # shrink :: C -> [C] #
Arbitrary OrdA # |
Instance details Defined in Test.QuickCheck.Poly Methods arbitrary :: Gen OrdA # shrink :: OrdA -> [OrdA] #
Arbitrary OrdB # |
Instance details Defined in Test.QuickCheck.Poly Methods arbitrary :: Gen OrdB # shrink :: OrdB -> [OrdB] #
Arbitrary OrdC # |
Instance details Defined in Test.QuickCheck.Poly Methods arbitrary :: Gen OrdC # shrink :: OrdC -> [OrdC] #
Arbitrary All # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen All # shrink :: All -> [All] #
Arbitrary Any # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Any # shrink :: Any -> [Any] #
Arbitrary Version # | Generates `Version` with non-empty non-negative `versionBranch`, and empty `versionTags`
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Version # shrink :: Version -> [Version] #
Arbitrary CChar # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CChar # shrink :: CChar -> [CChar] #
Arbitrary CClock # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CClock # shrink :: CClock -> [CClock] #
Arbitrary CDouble # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CDouble # shrink :: CDouble -> [CDouble] #
Arbitrary CFloat # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CFloat # shrink :: CFloat -> [CFloat] #
Arbitrary CInt # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CInt # shrink :: CInt -> [CInt] #
Arbitrary CIntMax # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CIntMax # shrink :: CIntMax -> [CIntMax] #
Arbitrary CIntPtr # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CIntPtr # shrink :: CIntPtr -> [CIntPtr] #
Arbitrary CLLong # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CLLong # shrink :: CLLong -> [CLLong] #
Arbitrary CLong # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CLong # shrink :: CLong -> [CLong] #
Arbitrary CPtrdiff # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CPtrdiff # shrink :: CPtrdiff -> [CPtrdiff] #
Arbitrary CSChar # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CSChar # shrink :: CSChar -> [CSChar] #
Arbitrary CSUSeconds # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CSUSeconds # shrink :: CSUSeconds -> [CSUSeconds] #
Arbitrary CShort # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CShort # shrink :: CShort -> [CShort] #
Arbitrary CSigAtomic # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CSigAtomic # shrink :: CSigAtomic -> [CSigAtomic] #
Arbitrary CSize # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CSize # shrink :: CSize -> [CSize] #
Arbitrary CTime # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CTime # shrink :: CTime -> [CTime] #
Arbitrary CUChar # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CUChar # shrink :: CUChar -> [CUChar] #
Arbitrary CUInt # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CUInt # shrink :: CUInt -> [CUInt] #
Arbitrary CUIntMax # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CUIntMax # shrink :: CUIntMax -> [CUIntMax] #
Arbitrary CUIntPtr # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CUIntPtr # shrink :: CUIntPtr -> [CUIntPtr] #
Arbitrary CULLong # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CULLong # shrink :: CULLong -> [CULLong] #
Arbitrary CULong # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CULong # shrink :: CULong -> [CULong] #
Arbitrary CUSeconds # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CUSeconds # shrink :: CUSeconds -> [CUSeconds] #
Arbitrary CUShort # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CUShort # shrink :: CUShort -> [CUShort] #
Arbitrary CWchar # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen CWchar # shrink :: CWchar -> [CWchar] #
Arbitrary ExitCode # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen ExitCode # shrink :: ExitCode -> [ExitCode] #
Arbitrary Newline # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Newline # shrink :: Newline -> [Newline] #
Arbitrary NewlineMode # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen NewlineMode # shrink :: NewlineMode -> [NewlineMode] #
Arbitrary Int16 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Int16 # shrink :: Int16 -> [Int16] #
Arbitrary Int32 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Int32 # shrink :: Int32 -> [Int32] #
Arbitrary Int64 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Int64 # shrink :: Int64 -> [Int64] #
Arbitrary Int8 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Int8 # shrink :: Int8 -> [Int8] #
Arbitrary Word16 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Word16 # shrink :: Word16 -> [Word16] #
Arbitrary Word32 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Word32 # shrink :: Word32 -> [Word32] #
Arbitrary Word64 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Word64 # shrink :: Word64 -> [Word64] #
Arbitrary Word8 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Word8 # shrink :: Word8 -> [Word8] #
Arbitrary IntSet # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen IntSet # shrink :: IntSet -> [IntSet] #
Arbitrary Ordering # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Ordering # shrink :: Ordering -> [Ordering] #
Arbitrary Integer # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Integer # shrink :: Integer -> [Integer] #
Arbitrary () # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen () # shrink :: () -> [()] #
Arbitrary Bool # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Bool # shrink :: Bool -> [Bool] #
Arbitrary Char # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Char # shrink :: Char -> [Char] #
Arbitrary Double # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Double # shrink :: Double -> [Double] #
Arbitrary Float # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Float # shrink :: Float -> [Float] #
Arbitrary Int # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Int # shrink :: Int -> [Int] #
Arbitrary Word # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen Word # shrink :: Word -> [Word] #
Arbitrary a => Arbitrary (Blind a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (Blind a) # shrink :: Blind a -> [Blind a] #
Arbitrary a => Arbitrary (Fixed a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (Fixed a) # shrink :: Fixed a -> [Fixed a] #
Arbitrary a => Arbitrary (InfiniteList a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (InfiniteList a) # shrink :: InfiniteList a -> [InfiniteList a] #
(Integral a, Bounded a) => Arbitrary (Large a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (Large a) # shrink :: Large a -> [Large a] #
(Num a, Ord a, Arbitrary a) => Arbitrary (Negative a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (Negative a) # shrink :: Negative a -> [Negative a] #
Arbitrary a => Arbitrary (NonEmptyList a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (NonEmptyList a) # shrink :: NonEmptyList a -> [NonEmptyList a] #
(Num a, Ord a, Arbitrary a) => Arbitrary (NonNegative a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (NonNegative a) # shrink :: NonNegative a -> [NonNegative a] #
(Num a, Ord a, Arbitrary a) => Arbitrary (NonPositive a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (NonPositive a) # shrink :: NonPositive a -> [NonPositive a] #
(Num a, Eq a, Arbitrary a) => Arbitrary (NonZero a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (NonZero a) # shrink :: NonZero a -> [NonZero a] #
(Ord a, Arbitrary a) => Arbitrary (OrderedList a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (OrderedList a) # shrink :: OrderedList a -> [OrderedList a] #
(Num a, Ord a, Arbitrary a) => Arbitrary (Positive a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (Positive a) # shrink :: Positive a -> [Positive a] #
Arbitrary a => Arbitrary (Shrink2 a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (Shrink2 a) # shrink :: Shrink2 a -> [Shrink2 a] #
Integral a => Arbitrary (Small a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (Small a) # shrink :: Small a -> [Small a] #
Arbitrary a => Arbitrary (Smart a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (Smart a) # shrink :: Smart a -> [Smart a] #
(Arbitrary a, Ord a) => Arbitrary (SortedList a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (SortedList a) # shrink :: SortedList a -> [SortedList a] #
Arbitrary a => Arbitrary (ZipList a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (ZipList a) # shrink :: ZipList a -> [ZipList a] #
Arbitrary a => Arbitrary (Complex a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Complex a) # shrink :: Complex a -> [Complex a] #
Arbitrary a => Arbitrary (Identity a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Identity a) # shrink :: Identity a -> [Identity a] #
Arbitrary a => Arbitrary (First a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (First a) # shrink :: First a -> [First a] #
Arbitrary a => Arbitrary (Last a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Last a) # shrink :: Last a -> [Last a] #
Arbitrary a => Arbitrary (Dual a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Dual a) # shrink :: Dual a -> [Dual a] #
(Arbitrary a, CoArbitrary a) => Arbitrary (Endo a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Endo a) # shrink :: Endo a -> [Endo a] #
Arbitrary a => Arbitrary (Product a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Product a) # shrink :: Product a -> [Product a] #
Arbitrary a => Arbitrary (Sum a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Sum a) # shrink :: Sum a -> [Sum a] #
Integral a => Arbitrary (Ratio a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Ratio a) # shrink :: Ratio a -> [Ratio a] #
Arbitrary a => Arbitrary (IntMap a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (IntMap a) # shrink :: IntMap a -> [IntMap a] #
Arbitrary a => Arbitrary (Seq a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Seq a) # shrink :: Seq a -> [Seq a] #
(Ord a, Arbitrary a) => Arbitrary (Set a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Set a) # shrink :: Set a -> [Set a] #
Arbitrary a => Arbitrary (Tree a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Tree a) # shrink :: Tree a -> [Tree a] #
Arbitrary a => Arbitrary (Maybe a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Maybe a) # shrink :: Maybe a -> [Maybe a] #
Arbitrary a => Arbitrary [a] # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen [a] # shrink :: [a] -> [[a]] #
(Function a, CoArbitrary a, Arbitrary b) => Arbitrary (a :-> b) # |
Instance details Defined in Test.QuickCheck.Function Methods arbitrary :: Gen (a :-> b) # shrink :: (a :-> b) -> [a :-> b] #
(Function a, CoArbitrary a, Arbitrary b) => Arbitrary (Fun a b) # |
Instance details Defined in Test.QuickCheck.Function Methods arbitrary :: Gen (Fun a b) # shrink :: Fun a b -> [Fun a b] #
(Arbitrary a, ShrinkState s a) => Arbitrary (Shrinking s a) # |
Instance details Defined in Test.QuickCheck.Modifiers Methods arbitrary :: Gen (Shrinking s a) # shrink :: Shrinking s a -> [Shrinking s a] #
Arbitrary (m a) => Arbitrary (WrappedMonad m a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (WrappedMonad m a) # shrink :: WrappedMonad m a -> [WrappedMonad m a] #
(Arbitrary a, Arbitrary b) => Arbitrary (Either a b) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Either a b) # shrink :: Either a b -> [Either a b] #
HasResolution a => Arbitrary (Fixed a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Fixed a) # shrink :: Fixed a -> [Fixed a] #
(Ord k, Arbitrary k, Arbitrary v) => Arbitrary (Map k v) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Map k v) # shrink :: Map k v -> [Map k v] #
(Arbitrary a, Arbitrary b) => Arbitrary (a, b) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (a, b) # shrink :: (a, b) -> [(a, b)] #
(CoArbitrary a, Arbitrary b) => Arbitrary (a -> b) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (a -> b) # shrink :: (a -> b) -> [a -> b] #
Arbitrary (a b c) => Arbitrary (WrappedArrow a b c) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (WrappedArrow a b c) # shrink :: WrappedArrow a b c -> [WrappedArrow a b c] #
Arbitrary a => Arbitrary (Const a b) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Const a b) # shrink :: Const a b -> [Const a b] #
Arbitrary (f a) => Arbitrary (Alt f a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Alt f a) # shrink :: Alt f a -> [Alt f a] #
Arbitrary a => Arbitrary (Constant a b) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (Constant a b) # shrink :: Constant a b -> [Constant a b] #
(Arbitrary a, Arbitrary b, Arbitrary c) => Arbitrary (a, b, c) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (a, b, c) # shrink :: (a, b, c) -> [(a, b, c)] #
(Arbitrary1 f, Arbitrary1 g, Arbitrary a) => Arbitrary (Product f g a) # |
Instance details Defined in Test.QuickCheck.Arbitrary 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 (a, b, c, d) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (a, b, c, d) # shrink :: (a, b, c, d) -> [(a, b, c, d)] #
(Arbitrary1 f, Arbitrary1 g, Arbitrary a) => Arbitrary (Compose f g a) # |
Instance details Defined in Test.QuickCheck.Arbitrary 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 (a, b, c, d, e) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods arbitrary :: Gen (a, b, c, d, e) # shrink :: (a, b, c, d, e) -> [(a, b, c, d, e)] #
(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d, Arbitrary e, Arbitrary f) => Arbitrary (a, b, c, d, e, f) # |
Instance details Defined in Test.QuickCheck.Arbitrary 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) # |
Instance details Defined in Test.QuickCheck.Arbitrary 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) # |
Instance details Defined in Test.QuickCheck.Arbitrary 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) # |
Instance details Defined in Test.QuickCheck.Arbitrary 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) # |
Instance details Defined in Test.QuickCheck.Arbitrary 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. You should consider using `Fun` instead, which can show the generated functions as strings.

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)`.

Minimal complete definition

Nothing

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)

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

#### Instances

Instances details

CoArbitrary A # |
Instance details Defined in Test.QuickCheck.Poly Methods coarbitrary :: A -> Gen b -> Gen b #
CoArbitrary B # |
Instance details Defined in Test.QuickCheck.Poly Methods coarbitrary :: B -> Gen b -> Gen b #
CoArbitrary C # |
Instance details Defined in Test.QuickCheck.Poly Methods coarbitrary :: C -> Gen b -> Gen b #
CoArbitrary OrdA # |
Instance details Defined in Test.QuickCheck.Poly Methods coarbitrary :: OrdA -> Gen b -> Gen b #
CoArbitrary OrdB # |
Instance details Defined in Test.QuickCheck.Poly Methods coarbitrary :: OrdB -> Gen b -> Gen b #
CoArbitrary OrdC # |
Instance details Defined in Test.QuickCheck.Poly Methods coarbitrary :: OrdC -> Gen b -> Gen b #
CoArbitrary All # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: All -> Gen b -> Gen b #
CoArbitrary Any # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Any -> Gen b -> Gen b #
CoArbitrary Version # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Version -> Gen b -> Gen b #
CoArbitrary Newline # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Newline -> Gen b -> Gen b #
CoArbitrary NewlineMode # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: NewlineMode -> Gen b -> Gen b #
CoArbitrary Int16 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Int16 -> Gen b -> Gen b #
CoArbitrary Int32 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Int32 -> Gen b -> Gen b #
CoArbitrary Int64 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Int64 -> Gen b -> Gen b #
CoArbitrary Int8 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Int8 -> Gen b -> Gen b #
CoArbitrary Word16 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Word16 -> Gen b -> Gen b #
CoArbitrary Word32 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Word32 -> Gen b -> Gen b #
CoArbitrary Word64 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Word64 -> Gen b -> Gen b #
CoArbitrary Word8 # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Word8 -> Gen b -> Gen b #
CoArbitrary IntSet # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: IntSet -> Gen b -> Gen b #
CoArbitrary Ordering # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Ordering -> Gen b -> Gen b #
CoArbitrary Integer # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Integer -> Gen b -> Gen b #
CoArbitrary () # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: () -> Gen b -> Gen b #
CoArbitrary Bool # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Bool -> Gen b -> Gen b #
CoArbitrary Char # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Char -> Gen b -> Gen b #
CoArbitrary Double # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Double -> Gen b -> Gen b #
CoArbitrary Float # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Float -> Gen b -> Gen b #
CoArbitrary Int # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Int -> Gen b -> Gen b #
CoArbitrary Word # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Word -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (ZipList a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: ZipList a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Complex a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Complex a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Identity a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Identity a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (First a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: First a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Last a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Last a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Dual a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Dual a -> Gen b -> Gen b #
(Arbitrary a, CoArbitrary a) => CoArbitrary (Endo a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Endo a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Product a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Product a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Sum a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Sum a -> Gen b -> Gen b #
(Integral a, CoArbitrary a) => CoArbitrary (Ratio a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Ratio a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (IntMap a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: IntMap a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Seq a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Seq a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Set a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Set a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Tree a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Tree a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Maybe a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Maybe a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary [a] # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: [a] -> Gen b -> Gen b #
(CoArbitrary a, CoArbitrary b) => CoArbitrary (Either a b) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Either a b -> Gen b0 -> Gen b0 #
HasResolution a => CoArbitrary (Fixed a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Fixed a -> Gen b -> Gen b #
(CoArbitrary k, CoArbitrary v) => CoArbitrary (Map k v) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Map k v -> Gen b -> Gen b #
(CoArbitrary a, CoArbitrary b) => CoArbitrary (a, b) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: (a, b) -> Gen b0 -> Gen b0 #
(Arbitrary a, CoArbitrary b) => CoArbitrary (a -> b) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: (a -> b) -> Gen b0 -> Gen b0 #
CoArbitrary a => CoArbitrary (Const a b) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Const a b -> Gen b0 -> Gen b0 #
CoArbitrary (f a) => CoArbitrary (Alt f a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Alt f a -> Gen b -> Gen b #
CoArbitrary a => CoArbitrary (Constant a b) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: Constant a b -> Gen b0 -> Gen b0 #
(CoArbitrary a, CoArbitrary b, CoArbitrary c) => CoArbitrary (a, b, c) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: (a, b, c) -> Gen b0 -> Gen b0 #
(CoArbitrary a, CoArbitrary b, CoArbitrary c, CoArbitrary d) => CoArbitrary (a, b, c, d) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: (a, b, c, d) -> Gen b0 -> Gen b0 #
(CoArbitrary a, CoArbitrary b, CoArbitrary c, CoArbitrary d, CoArbitrary e) => CoArbitrary (a, b, c, d, e) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods coarbitrary :: (a, b, c, d, e) -> Gen b0 -> Gen b0 #

## 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

Instances details

Arbitrary1 ZipList # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary :: Gen a -> Gen (ZipList a) # liftShrink :: (a -> [a]) -> ZipList a -> [ZipList a] #
Arbitrary1 Identity # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary :: Gen a -> Gen (Identity a) # liftShrink :: (a -> [a]) -> Identity a -> [Identity a] #
Arbitrary1 IntMap # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary :: Gen a -> Gen (IntMap a) # liftShrink :: (a -> [a]) -> IntMap a -> [IntMap a] #
Arbitrary1 Seq # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary :: Gen a -> Gen (Seq a) # liftShrink :: (a -> [a]) -> Seq a -> [Seq a] #
Arbitrary1 Tree # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary :: Gen a -> Gen (Tree a) # liftShrink :: (a -> [a]) -> Tree a -> [Tree a] #
Arbitrary1 Maybe # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary :: Gen a -> Gen (Maybe a) # liftShrink :: (a -> [a]) -> Maybe a -> [Maybe a] #
Arbitrary1 List # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary :: Gen a -> Gen [a] # liftShrink :: (a -> [a]) -> [a] -> [[a]] #
Arbitrary a => Arbitrary1 (Either a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary :: Gen a0 -> Gen (Either a a0) # liftShrink :: (a0 -> [a0]) -> Either a a0 -> [Either a a0] #
(Ord k, Arbitrary k) => Arbitrary1 (Map k) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary :: Gen a -> Gen (Map k a) # liftShrink :: (a -> [a]) -> Map k a -> [Map k a] #
Arbitrary a => Arbitrary1 ((,) a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary :: Gen a0 -> Gen (a, a0) # liftShrink :: (a0 -> [a0]) -> (a, a0) -> [(a, a0)] #
Arbitrary a => Arbitrary1 (Const a :: Type -> Type) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary :: Gen a0 -> Gen (Const a a0) # liftShrink :: (a0 -> [a0]) -> Const a a0 -> [Const a a0] #
Arbitrary a => Arbitrary1 (Constant a :: Type -> Type) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary :: Gen a0 -> Gen (Constant a a0) # liftShrink :: (a0 -> [a0]) -> Constant a a0 -> [Constant a a0] #
(Arbitrary1 f, Arbitrary1 g) => Arbitrary1 (Product f g) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary :: Gen a -> Gen (Product f g a) # liftShrink :: (a -> [a]) -> Product f g a -> [Product f g a] #
CoArbitrary a => Arbitrary1 ((->) a) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary :: Gen a0 -> Gen (a -> a0) # liftShrink :: (a0 -> [a0]) -> (a -> a0) -> [a -> a0] #
(Arbitrary1 f, Arbitrary1 g) => Arbitrary1 (Compose f g) # |
Instance details Defined in Test.QuickCheck.Arbitrary 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

Instances details

Arbitrary2 Either # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary2 :: Gen a -> Gen b -> Gen (Either a b) # liftShrink2 :: (a -> [a]) -> (b -> [b]) -> Either a b -> [Either a b] #
Arbitrary2 (,) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary2 :: Gen a -> Gen b -> Gen (a, b) # liftShrink2 :: (a -> [a]) -> (b -> [b]) -> (a, b) -> [(a, b)] #
Arbitrary2 (Const :: Type -> Type -> Type) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary2 :: Gen a -> Gen b -> Gen (Const a b) # liftShrink2 :: (a -> [a]) -> (b -> [b]) -> Const a b -> [Const a b] #
Arbitrary2 (Constant :: Type -> Type -> Type) # |
Instance details Defined in Test.QuickCheck.Arbitrary 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

applyArbitrary2 :: (Arbitrary a, Arbitrary b) => (a -> b -> r) -> Gen r #

Apply a binary function to random arguments.

applyArbitrary3 :: (Arbitrary a, Arbitrary b, Arbitrary c) => (a -> b -> c -> r) -> Gen r #

Apply a ternary function to random arguments.

applyArbitrary4 :: (Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d) => (a -> b -> c -> d -> r) -> Gen r #

Apply a function of arity 4 to random arguments.

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 #

Uniformly 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

class RecursivelyShrink f #

Minimal complete definition

grecursivelyShrink

#### Instances

Instances details

RecursivelyShrink (U1 :: k -> Type) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods grecursivelyShrink :: forall (a :: k0). U1 a -> [U1 a]
RecursivelyShrink (V1 :: k -> Type) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods grecursivelyShrink :: forall (a :: k0). V1 a -> [V1 a]
(RecursivelyShrink f, RecursivelyShrink g) => RecursivelyShrink (f :*: g :: k -> Type) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods grecursivelyShrink :: forall (a :: k0). (f :*: g) a -> [(f :*: g) a]
(RecursivelyShrink f, RecursivelyShrink g) => RecursivelyShrink (f :+: g :: k -> Type) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods grecursivelyShrink :: forall (a :: k0). (f :+: g) a -> [(f :+: g) a]
Arbitrary a => RecursivelyShrink (K1 i a :: k -> Type) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods grecursivelyShrink :: forall (a0 :: k0). K1 i a a0 -> [K1 i a a0]
RecursivelyShrink f => RecursivelyShrink (M1 i c f :: k -> Type) # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods grecursivelyShrink :: forall (a :: k0). M1 i c f a -> [M1 i c f a]

class GSubterms f a #

Minimal complete definition

gSubterms

#### Instances

Instances details

GSubterms (U1 :: Type -> Type) a # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods gSubterms :: U1 a -> [a]
GSubterms (V1 :: Type -> Type) a # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods gSubterms :: V1 a -> [a]
(GSubtermsIncl f a, GSubtermsIncl g a) => GSubterms (f :*: g) a # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods gSubterms :: (f :*: g) a -> [a]
(GSubtermsIncl f a, GSubtermsIncl g a) => GSubterms (f :+: g) a # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods gSubterms :: (f :+: g) a -> [a]
GSubterms (K1 i a :: Type -> Type) b # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods gSubterms :: K1 i a b -> [b]
GSubterms f a => GSubterms (M1 i c f) a # |
Instance details Defined in Test.QuickCheck.Arbitrary Methods gSubterms :: M1 i c f a -> [a]

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, preferring numbers with smaller numerators or denominators. See also `shrinkDecimal`.

shrinkBoundedEnum :: (Bounded a, Enum a, Eq a) => a -> [a] #

Shrink an element of a bounded enumeration.

### Example

Expand

    data MyEnum = E0 | E1 | E2 | E3 | E4 | E5 | E6 | E7 | E8 | E9
       deriving (Bounded, Enum, Eq, Ord, Show)

    >>> shrinkBoundedEnum E9
    [E0,E5,E7,E8]

    >>> shrinkBoundedEnum E5
    [E0,E3,E4]

    >>> shrinkBoundedEnum E0
    []

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

Shrink a real number, preferring numbers with shorter decimal representations. See also `shrinkRealFrac`.

## 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.