parseDouble :: ReadP Double
parseDouble = do a <- munch1 isDigit
                 b <- satisfy (== '.')
                 c <- munch1 isDigit
                 return $ read (a ++ [b] ++ c)
parseDouble :: ReadP Double
parseDouble = do a <- munch1 isDigit
                 b <- satisfy (== '.')
                 c <- munch1 isDigit
                 return $ read (a ++ [b] ++ c)
parseDouble = do a <- munch1 isDigit
                 b <- satisfy (== '.')
                 c <- munch1 isDigit
                 return $ read (a ++ [b] ++ c)