{-# OPTIONS -fglasgow-exts #-} -- These are simple tests to observe (data)type representations. module Datatype where import Test.HUnit import Data.Tree import Data.Generics -- A simple polymorphic datatype data MyDataType a = MyDataType a deriving (Typeable, Data) -- Some terms and corresponding type representations myTerm = undefined :: MyDataType Int myTypeRep = typeOf myTerm -- type representation in Typeable myTyCon = typeRepTyCon myTypeRep -- type constructor via Typeable myDataType = dataTypeOf myTerm -- datatype representation in Data myString1 = tyConName myTyCon -- type constructor via Typeable myString2 = dataTypeName myDataType -- type constructor via Data -- Main function for testing tests = show ( myTypeRep , ( myDataType , ( tyconModule myString1 , ( tyconUQname myString1 , ( tyconModule myString2 , ( tyconUQname myString2 )))))) ~=? output output = "(MyDataType Int,(DataType {tycon = \"Datatype.MyDataType\", datarep = AlgRep [MyDataType]},(\"\",(\"MyDataType\",(\"Datatype\",\"MyDataType\")))))"