execution result

~$ stack runhaskell myshow.hs 
Run from outside a project, using implicit global project config
Using resolver: lts-5.1 from implicit global project's config file: /home/nushio/.stack/global-project/stack.yaml
individual representations test:
  ushow "\28450\&6" == "漢6": [OK]
  ushow "\na\ri\ta \22269\38555\31354\28207" == "\na\ri\ta 国際空港": [Failed]
expected: "\"\\na\\ri\\ta \22269\38555\31354\28207\""
 but got: "\"\na\ri\ta \22269\38555\31354\28207\""
  ushow "\SOH\SO\&H" == "\SOH\SO\&H": [Failed]
expected: "\"\\SOH\\SO\\&H\""
 but got: "\"\SOH\SO\&H\""
read . ushow == id:
  read . ushow == id, for String: [Failed]
*** Failed! Exception: 'Prelude.read: no parse' (after 16 tests and 4 shrinks): 
"\""
(used seed 1488425704269779283)
  read . read . ushow . ushow == id, for String: [Failed]
*** Failed! Exception: 'Prelude.read: no parse' (after 1 test): 
""
(used seed 7384686312765896853)
  read . ushow == id, for some crazy Unicode type: [Failed]
*** Failed! Exception: 'Prelude.read: no parse' (after 19 tests and 2 shrinks): 
"\""
(used seed -7705745822685319130)
  read . ushow == id, for some crazy Unicode type: [Failed]
*** Failed! Exception: 'Prelude.read: no parse' (after 28 tests and 6 shrinks): 
""
"\\"
(used seed -2988398841461806209)
  read . ushow == id, for compound type: [Failed]
*** Failed! Exception: 'Prelude.read: no parse' (after 7 tests and 6 shrinks): 
Left ["\""]
(used seed -9135237574203273231)

         Properties  Test Cases  Total      
 Passed  0           1           1          
 Failed  5           2           7          
 Total   5           3           8  

myshow.hs

{-# LANGUAGE ScopedTypeVariables #-}


import Test.Framework (defaultMain, testGroup)
import Test.Framework.Providers.API (Test)
import Test.Framework.Providers.HUnit (testCase)
import Test.Framework.Providers.QuickCheck2 (testProperty)
import Test.HUnit.Base hiding (Test)




ushow :: Show a => a -> String
ushow x = go (show x) where
      go :: String -> String
      go [] = []
      go s@(x:xs) = case x of
          '\"' -> '\"' : str ++ "\"" ++ go rest
          '\'' -> '\'' : char : '\'' : go rest'
          _    -> x : go xs
        where
          (str :: String, rest):_ = reads s
          (char :: Char, rest'):_ = reads s

data T試6験 = Å4 { すけろく :: String} deriving (Eq, Ord, Show, Read)
data T試7験 = String :\& String  deriving (Eq, Ord, Show, Read)

-- Derived instance of Read and Show produced by GHC
-- does not satisfy Haskell 2010 spec, for the moment (ghc 7.10.3).
-- Therefore, we must regretfully skip this test.
data T試8験 = String :＠\& String  deriving (Eq, Ord, Show, Read)


ushowTo :: Show a => a -> String -> Test
ushowTo f t = testCase ("ushow " ++ show f ++ " == " ++ t) $ t @=? ushow f

tests :: [Test]
tests =
  [ testGroup "individual representations test"
    [
      "漢6" `ushowTo` "\"漢6\""
    , "\na\ri\ta 国際空港" `ushowTo` "\"\\na\\ri\\ta 国際空港\""
    , "\SOH\SO\&H" `ushowTo` "\"\\SOH\\SO\\&H\""
    ]

  , testGroup "read . ushow == id"
    [ testProperty "read . ushow == id, for String" $
      \str -> read (ushow str) == (str :: String)
    , testProperty "read . read . ushow . ushow == id, for String" $
      \str -> (read $ read $ ushow $ ushow str) == (str :: String)
    , testProperty "read . ushow == id, for some crazy Unicode type" $
      \str -> let v = Å4 str in read (ushow v) == v
    , testProperty "read . ushow == id, for some crazy Unicode type" $
      \a b -> let v = a :\& b in read (ushow v) == v
--     , testProperty "read . ushow == id, for some crazy Unicode type" $
--       \a b -> let v = a :＠\& b in read (show v) == v
    , testProperty "read . ushow == id, for compound type" $
      \str -> read (ushow str) == (str :: Either [String] (String,String))
    ]
  ]
main :: IO ()
main = defaultMain tests