commit a0d8bcde5ab5329d11be8cd89c407e6aa0db83a4
Author: Fumiaki Kinoshita <fumiexcel@gmail.com>
Date:   Tue Apr 30 18:37:40 2019 +0900

    Support GHC 8.8

diff --git a/Text/JSON.hs b/Text/JSON.hs
index f2e2618..6f80949 100644
--- a/Text/JSON.hs
+++ b/Text/JSON.hs
@@ -37,7 +37,7 @@ module Text.JSON (
     -- ** Instance helpers
   , makeObj, valFromObj
   , JSKey(..), encJSDict, decJSDict
-  
+
   ) where
 
 import Text.JSON.Types
@@ -60,7 +60,7 @@ import qualified Data.Text as T
 
 ------------------------------------------------------------------------
 
--- | Decode a String representing a JSON value 
+-- | Decode a String representing a JSON value
 -- (either an object, array, bool, number, null)
 --
 -- This is a superset of JSON, as types other than
@@ -137,7 +137,9 @@ instance MonadPlus Result where
 
 instance Monad Result where
   return x      = Ok x
+#if !MIN_VERSION_base(4,13,0)
   fail x        = Error x
+#endif
   Ok a >>= f    = f a
   Error x >>= _ = Error x
 
@@ -199,7 +201,7 @@ instance JSON Ordering where
   showJSON = encJSString show
   readJSON = decJSString "Ordering" readOrd
     where
-     readOrd x = 
+     readOrd x =
        case x of
          "LT" -> return Prelude.LT
          "EQ" -> return Prelude.EQ
@@ -460,7 +462,7 @@ instance JSKey Int where
 instance JSKey String where
   toJSKey   = id
   fromJSKey = Just
-  
+
 -- | Encode an association list as 'JSObject' value.
 encJSDict :: (JSKey a, JSON b) => [(a,b)] -> JSValue
 encJSDict v = makeObj [ (toJSKey x, showJSON y) | (x,y) <- v ]
@@ -477,5 +479,3 @@ decJSDict l (JSObject o) = mapM rd (fromJSObject o)
                                     "unable to read dict; invalid object key")
 
 decJSDict l _ = mkError ("readJSON{"++l ++ "}: unable to read dict; expected JSON object")
-
-
diff --git a/Text/JSON/String.hs b/Text/JSON/String.hs
index 51463cd..67fdca8 100644
--- a/Text/JSON/String.hs
+++ b/Text/JSON/String.hs
@@ -1,7 +1,8 @@
+{-# LANGUAGE CPP #-}
 -- | Basic support for working with JSON values.
 
-module Text.JSON.String 
-     ( 
+module Text.JSON.String
+     (
        -- * Parsing
        --
        GetJSON
@@ -35,6 +36,7 @@ import Text.JSON.Types (JSValue(..),
                         JSObject, toJSObject, fromJSObject)
 
 import Control.Monad (liftM, ap)
+import qualified Control.Monad.Fail as Fail
 import Control.Applicative((<$>))
 import qualified Control.Applicative as A
 import Data.Char (isSpace, isDigit, digitToInt)
@@ -52,9 +54,14 @@ instance A.Applicative GetJSON where
   pure  = return
   (<*>) = ap
 
+instance Fail.MonadFail GetJSON where
+  fail x          = GetJSON (\_ -> Left x)
+
 instance Monad GetJSON where
   return x        = GetJSON (\s -> Right (x,s))
-  fail x          = GetJSON (\_ -> Left x)
+#if !MIN_VERSION_base(4,13,0)
+  fail = Fail.fail
+#endif
   GetJSON m >>= f = GetJSON (\s -> case m s of
                                      Left err -> Left err
                                      Right (a,s1) -> un (f a) s1)
@@ -93,7 +100,7 @@ tryJSNull k = do
   xs <- getInput
   case xs of
     'n':'u':'l':'l':xs1 -> setInput xs1 >> return JSNull
-    _ -> k 
+    _ -> k
 
 -- | Read the JSON Bool type
 readJSBool :: GetJSON JSValue
@@ -111,8 +118,8 @@ readJSString = do
   case x of
        '"' : cs -> parse [] cs
        _        -> fail $ "Malformed JSON: expecting string: " ++ context x
- where 
-  parse rs cs = 
+ where
+  parse rs cs =
     case cs of
       '\\' : c : ds -> esc rs c ds
       '"'  : ds     -> do setInput ds
@@ -153,22 +160,22 @@ readJSRational = do
     '-' : ds -> negate <$> pos ds
     _        -> pos cs
 
-  where 
+  where
    pos []     = fail $ "Unable to parse JSON Rational: " ++ context []
    pos (c:cs) =
      case c of
        '0' -> frac 0 cs
-       _ 
+       _
         | not (isDigit c) -> fail $ "Unable to parse JSON Rational: " ++ context cs
         | otherwise -> readDigits (digitToIntI c) cs
 
    readDigits acc [] = frac (fromInteger acc) []
    readDigits acc (x:xs)
-    | isDigit x = let acc' = 10*acc + digitToIntI x in 
+    | isDigit x = let acc' = 10*acc + digitToIntI x in
                       acc' `seq` readDigits acc' xs
     | otherwise = frac (fromInteger acc) (x:xs)
 
-   frac n ('.' : ds) = 
+   frac n ('.' : ds) =
        case span isDigit ds of
          ([],_) -> setInput ds >> return n
          (as,bs) -> let x = read as :: Integer
@@ -320,15 +327,15 @@ showJSRational :: Rational -> ShowS
 showJSRational r = showJSRational' False r
 
 showJSRational' :: Bool -> Rational -> ShowS
-showJSRational' asFloat r 
+showJSRational' asFloat r
  | denominator r == 1      = shows $ numerator r
  | isInfinite x || isNaN x = showJSNull
  | asFloat                 = shows xf
  | otherwise               = shows x
- where 
+ where
    x :: Double
    x = realToFrac r
-   
+
    xf :: Float
    xf = realToFrac r
 
@@ -382,4 +389,3 @@ encJSString jss ss = go (fromJSString jss)
       | x < '\x1000' -> 'u' : '0' : hexxs
       | otherwise    -> 'u' : hexxs
       where hexxs = showHex (fromEnum x) xs
-