parseNumber :: Parser LispVal
parseNumber = try (parseOctalNumber
               <|> parseHexNumber
               <|> parseBinaryNumber
               <|> parseDecimalNumber)
parseNumber :: Parser LispVal
parseNumber = try (parseOctalNumber
               <|> parseHexNumber
               <|> parseBinaryNumber
               <|> parseDecimalNumber)
parseNumber = try (parseOctalNumber
               <|> parseHexNumber
               <|> parseBinaryNumber
               <|> parseDecimalNumber)