f84e051 · typeable/generic-arbitrary

generic-arbitrary.cabal+2−1

compare with master

unifiedsplit

@@ -67,7 +67,8 @@ test-suite test

67 , tasty-discover

68 , tasty-hunit

69 , tasty-quickcheck

70+ other-modules: LimitationDemo

70− other-modules: NoTypecheckTest

71+ , NoTypecheckTest

71 , RecursiveTest

72 , RecursiveTest

72 default-extensions: AllowAmbiguousTypes

73 default-extensions: AllowAmbiguousTypes

73 , CPP

74 , CPP

src/Test/QuickCheck/Arbitrary/Generic.hs+1−1

@@ -53,7 +53,7 @@ newtype GenericArbitrary a = GenericArbitrary { unGenericArbitrary :: a }

53

54instance

55 ( Generic a,

56− GArbitrary a (Rep a) 'True,

56+ GArbitrary a (Rep a) some,

57 RecursivelyShrink (Rep a),

58 GSubterms (Rep a) a

59 ) => Arbitrary (GenericArbitrary a) where

test/LimitationDemo.hsnew file+30

@@ -0,0 +1,30 @@

1+{-# LANGUAGE NumDecimals #-}

2+{-# LANGUAGE DerivingStrategies #-}

3+{-# LANGUAGE DerivingVia #-}

4+{-# LANGUAGE DeriveAnyClass #-}

5+

6+module LimitationDemo where

7+

8+import Control.DeepSeq

9+import GHC.Generics (Generic)

10+import Test.QuickCheck

11+import Test.QuickCheck.Arbitrary.Generic

12+

13+-- As you can see, we have this instance generated, but it will definitely lead

14+-- to generating an infinite term (and the only term). The recursion detection

15+-- doesn't work here

16+data R1 = R1 R2

17+ deriving (Eq, Ord, Show, Generic)

18+ deriving anyclass NFData

19+ deriving Arbitrary via (GenericArbitrary R1)

20+

21+data R2 = R2 R1

22+ deriving (Eq, Ord, Show, Generic)

23+ deriving anyclass NFData

24+ deriving Arbitrary via (GenericArbitrary R2)

25+

26+-- To force the instance realy be generated

27+usage :: IO ()

28+usage = do

29+ r1 :: R1 <- generate arbitrary

30+ print r1 -- haha