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GHC.Read Portability non-portable (GHC Extensions) Stability internal Maintainer cvs-ghc@haskell.org

Description

The Read class and instances for basic data types.

Synopsis

class Read a where readsPrec :: Int -> ReadS a readList :: ReadS [a] readPrec :: ReadPrec a readListPrec :: ReadPrec [a] type ReadS a = String -> [(a, String)] reads :: (Read a) => ReadS a readp :: (Read a) => ReadP a readEither :: (Read a) => String -> Either String a read :: (Read a) => String -> a lex :: ReadS String lexLitChar :: ReadS String readLitChar :: ReadS Char lexDigits :: ReadS String lexP :: ReadPrec Lexeme paren :: ReadPrec a -> ReadPrec a parens :: ReadPrec a -> ReadPrec a list :: ReadPrec a -> ReadPrec [a] choose :: [(String, ReadPrec a)] -> ReadPrec a readListDefault :: (Read a) => ReadS [a] readListPrecDefault :: (Read a) => ReadPrec [a] readList__ :: ReadS a -> ReadS [a] readParen :: Bool -> ReadS a -> ReadS a

Documentation

class Read a where

Methods readsPrec :: Int -> ReadS a readList :: ReadS [a] readPrec :: ReadPrec a readListPrec :: ReadPrec [a] Instances Read CChar Read CSChar Read CUChar Read CShort Read CUShort Read CInt Read CUInt Read CLong Read CULong Read CLLong Read CULLong Read CFloat Read CDouble Read CLDouble Read CPtrdiff Read CSize Read CWchar Read CSigAtomic Read CClock Read CTime Read Int8 Read Int16 Read Int32 Read Int64 Read Char Read Bool Read Ordering (Read a) => Read (Maybe a) (Read a, Read b) => Read (Either a b) (Read a) => Read [a] (Ix a, Read a, Read b) => Read (Array a b) Read Lexeme Read Int Read Integer Read Float Read Double (Integral a, Read a) => Read (Ratio a) Read () (Read a, Read b) => Read (a, b) (Read a, Read b, Read c) => Read (a, b, c) (Read a, Read b, Read c, Read d) => Read (a, b, c, d) (Read a, Read b, Read c, Read d, Read e) => Read (a, b, c, d, e) Read Word Read Word8 Read Word16 Read Word32 Read Word64 Read StdGen

type ReadS a = String -> [(a, String)]

A parser for a type a, represented as a function that takes a String and returns a list of possible parses (a,String) pairs.

reads :: (Read a) => ReadS a

readp :: (Read a) => ReadP a

readEither :: (Read a) => String -> Either String a

read :: (Read a) => String -> a

lex :: ReadS String

lexLitChar :: ReadS String

readLitChar :: ReadS Char

lexDigits :: ReadS String

lexP :: ReadPrec Lexeme

Parse a single lexeme

paren :: ReadPrec a -> ReadPrec a

(paren p) parses (P0) where p parses P0 in precedence context zero

parens :: ReadPrec a -> ReadPrec a

(parens p) parses P, (P0), ((P0)), etc, where p parses P in the current precedence context parses P0 in precedence context zero

list :: ReadPrec a -> ReadPrec [a]

(list p) parses a list of things parsed by p, using the usual square-bracket syntax.

choose :: [(String, ReadPrec a)] -> ReadPrec a

Parse the specified lexeme and continue as specified. Esp useful for nullary constructors; e.g. choose [(A, return A), (B, return B)]

readListDefault :: (Read a) => ReadS [a]

Use this to define the readList method, if you don't want a special case

readListPrecDefault :: (Read a) => ReadPrec [a]

Use this to define the readListPrec method, if you don't want a special case

readList__ :: ReadS a -> ReadS [a]

readParen :: Bool -> ReadS a -> ReadS a

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