megaparsec/Text/Parsec/String.hs

40 lines
1.3 KiB
Haskell

-----------------------------------------------------------------------------
-- |
-- Module : Text.Parsec.String
-- Copyright : (c) Paolo Martini 2007
-- License : BSD-style (see the file libraries/parsec/LICENSE)
--
-- Maintainer : derek.a.elkins@gmail.com
-- Stability : provisional
-- Portability : portable
--
-- Make Strings an instance of 'Stream' with 'Char' token type.
--
-----------------------------------------------------------------------------
{-# LANGUAGE FlexibleInstances #-}
module Text.Parsec.String
( Parser, GenParser, parseFromFile
) where
import Text.Parsec.Error
import Text.Parsec.Prim
type Parser = Parsec String ()
type GenParser tok st = Parsec [tok] st
-- | @parseFromFile p filePath@ runs a string parser @p@ on the
-- input read from @filePath@ using 'Prelude.readFile'. Returns either a 'ParseError'
-- ('Left') or a value of type @a@ ('Right').
--
-- > main = do{ result <- parseFromFile numbers "digits.txt"
-- > ; case result of
-- > Left err -> print err
-- > Right xs -> print (sum xs)
-- > }
parseFromFile :: Parser a -> String -> IO (Either ParseError a)
parseFromFile p fname
= do input <- readFile fname
return (runP p () fname input)