T12921.hs:4:1: error: [GHC-39999]
    • Ambiguous type variable ‘a0’ arising from an annotation
      prevents the constraint ‘(Data.Data.Data a0)’ from being solved.
      Probable fix: use a type annotation to specify what ‘a0’ should be.
      Potentially matching instances:
        instance (Data.Data.Data a, Data.Data.Data b) =>
                 Data.Data.Data (Either a b)
          -- Defined in ‘Data.Data’
        instance Data.Data.Data Ordering -- Defined in ‘Data.Data’
        ...plus 17 others
        ...plus 50 instances involving out-of-scope types
        (use -fprint-potential-instances to see them all)
    • In the annotation:
        {-# ANN module "HLint: ignore Reduce duplication" #-}

T12921.hs:4:16: error: [GHC-39999]
    • Ambiguous type variable ‘a0’ arising from the literal ‘"HLint: ignore Reduce duplication"’
      prevents the constraint ‘(Data.String.IsString
                                  a0)’ from being solved.
      Probable fix: use a type annotation to specify what ‘a0’ should be.
      Potentially matching instance:
        instance (a ~ Char) => Data.String.IsString [a]
          -- Defined in ‘Data.String’
        ...plus two instances involving out-of-scope types
        (use -fprint-potential-instances to see them all)
    • In the annotation:
        {-# ANN module "HLint: ignore Reduce duplication" #-}

T12921.hs:7:8: error: [GHC-88464]
    Variable not in scope: choice :: [a0] -> Int -> Int