beauty.hs

number = do w <- whole
            return $ Number $ read w
     <|> do f <- fraction
            return $ Number $ read ('0':f)
     <|> do w <- whole
            f <- fraction
            return $ Number $ read (w ++ f)
            where whole    = many1 digit
                  fraction = do char '.'
                                a <- many1 digit
                                return $ '.':a