-- | @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)
parseFromFile :: Parser a -> String -> IO (Either ParseError a)
parseFromFile p fname
    = do input <- readFile fname
         return (runP p () fname input)
parseFromFile p fname
    = do input <- readFile fname
         return (runP p () fname input)