{-# LANGUAGE Trustworthy #-}
{-# LANGUAGE NoImplicitPrelude #-}
module Text.Read (
   
   Read(..),
   ReadS,
   
   reads,
   read,
   readParen,
   lex,
   
   module Text.ParserCombinators.ReadPrec,
   L.Lexeme(..),
   lexP,
   parens,
   readListDefault,
   readListPrecDefault,
   readEither,
   readMaybe
 ) where
import GHC.Base
import GHC.Read
import Data.Either
import Text.ParserCombinators.ReadP as P
import Text.ParserCombinators.ReadPrec
import qualified Text.Read.Lex as L
reads :: Read a => ReadS a
reads :: forall a. Read a => ReadS a
reads = Int -> ReadS a
forall a. Read a => Int -> ReadS a
readsPrec Int
minPrec
readEither :: Read a => String -> Either String a
readEither :: forall a. Read a => String -> Either String a
readEither String
s =
  case [ a
x | (a
x,String
"") <- ReadPrec a -> Int -> ReadS a
forall a. ReadPrec a -> Int -> ReadS a
readPrec_to_S ReadPrec a
read' Int
minPrec String
s ] of
    [a
x] -> a -> Either String a
forall a b. b -> Either a b
Right a
x
    []  -> String -> Either String a
forall a b. a -> Either a b
Left String
"Prelude.read: no parse"
    [a]
_   -> String -> Either String a
forall a b. a -> Either a b
Left String
"Prelude.read: ambiguous parse"
 where
  read' :: ReadPrec a
read' =
    do a
x <- ReadPrec a
forall a. Read a => ReadPrec a
readPrec
       ReadP () -> ReadPrec ()
forall a. ReadP a -> ReadPrec a
lift ReadP ()
P.skipSpaces
       a -> ReadPrec a
forall a. a -> ReadPrec a
forall (m :: * -> *) a. Monad m => a -> m a
return a
x
readMaybe :: Read a => String -> Maybe a
readMaybe :: forall a. Read a => String -> Maybe a
readMaybe String
s = case String -> Either String a
forall a. Read a => String -> Either String a
readEither String
s of
                Left String
_  -> Maybe a
forall a. Maybe a
Nothing
                Right a
a -> a -> Maybe a
forall a. a -> Maybe a
Just a
a
read :: Read a => String -> a
read :: forall a. Read a => String -> a
read String
s = (String -> a) -> (a -> a) -> Either String a -> a
forall a c b. (a -> c) -> (b -> c) -> Either a b -> c
either String -> a
forall a. String -> a
errorWithoutStackTrace a -> a
forall a. a -> a
id (String -> Either String a
forall a. Read a => String -> Either String a
readEither String
s)