T12921.hs:4:1: error:
    • Ambiguous type variable ‘p0’ arising from an annotation
      prevents the constraint ‘(Data.Data.Data p0)’ from being solved.
      Probable fix: use a type annotation to specify what ‘p0’ should be.
      These potential instances exist:
        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’
        instance Data.Data.Data Integer -- Defined in ‘Data.Data’
        ...plus 15 others
        ...plus 47 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:
    • Ambiguous type variable ‘p0’ arising from the literal ‘"HLint: ignore Reduce duplication"’
      prevents the constraint ‘(Data.String.IsString
                                  p0)’ from being solved.
      Probable fix: use a type annotation to specify what ‘p0’ should be.
      These potential instances exist:
        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:
    Variable not in scope: choice :: [a0] -> Int -> Int