输出haskell对象,忽略“show”声明

如何将Haskell对象作为有效Haskell代码的字符串输出到忽略现有 show 声明?

例如,我有以下类型声明和相应的 显示 声明( check the code out in an online IDE ):

{-# LANGUAGE TypeSynonymInstances, FlexibleInstances #-}

import Data.Maybe

type VersionCompound = Maybe Int

data VersionNumber = VersionNumber [VersionCompound] deriving (Show)

data MaturityLevel = Dev
                   | Test
                   | User
                   | ReleaseCandidate
                   | Prod
                   deriving (Show)

data Version = MaturityVersion MaturityLevel VersionNumber  
     | Version VersionNumber

class ToString a where
    toString :: a -> String

instance ToString VersionCompound where
    toString (Just n) = (show n)
    toString Nothing = "x"

instance ToString [VersionCompound] where
    toString [] = "" 
    toString (x:[]) = (toString x)
    toString (x:xs) = (toString x) ++ "." ++ (toString xs) 

instance ToString VersionNumber where
    toString (VersionNumber []) = "" 
    toString (VersionNumber (x:[])) = (toString x) 
    toString (VersionNumber (x:xs)) = (toString x) ++ "." ++ (toString xs)

instance ToString Version where
    toString (MaturityVersion maturityLevel versionNumber) = (show maturityLevel) ++ "/" ++ (toString versionNumber)
    toString (Version versionNumber) = (toString versionNumber)

instance Show Version where
    show version = toString version

main = putStrLn $ show (Version $ VersionNumber [ Just 1, Just 2, Nothing])

该程序的输出为:

1.2.x

但有没有办法以有效的Haskell代码的形式输出对象?例如,对于上面的代码 showIntact $ Version $ VersionNumber [ Just 1, Just 2, Nothing] 将输出如下内容:

Version ( VersionNumber [ Just 1, Just 2, Nothing] )