Scala program to translate between HEX and ASCII

HexLib.scala

// Program to encode/decode hexadecimal and ASCII/Unicode

/**
* Decodes a string of hexadecimal numbers into a string of characters.
*
* @param input A string with only valid HEX numbers separated by spaces and/or commas.
*/
def decodeHex(input: String): String = {
    input
        .split("(\\s|,)+")                                                      // Split into individual values
        .map(Integer.parseInt(_, 16))                                           // Parse as hex into numbers
        .map(_.toChar)                                                          // Convert numbers to ASCII
        .mkString;                                                              // Merge results into a string
}

/**
* Converts a regular string into the equivalent hexadecimal values.
*
* @param input Any string of valid ASCII/Unicode characters.
*/
def encodeHex(input: String): String = {
    input
        .map(_.toInt.toHexString)                                               // Convert to number, then hex
        .mkString(" ");                                                         // Merge with space separators
}

/** Main Program */
@main def HexLib() : Unit = {
    print("(E)ncode, (D)ecode, or (Q)uit?\n> ");
    val opt = Console.in.readLine().charAt(0);                                  // Prompt to select function

    opt match {
        case 'e' | 'E' => {                                                     // Encode to HEX
            print("Enter string to encode.\n> ");
            println("= " + encodeHex(Console.in.readLine()) + "\n");
            HexLib();
        }

        case 'f' | 'F' => {                                                     // Press F to pay respects.
            println("Respects have been paid.\n")
            HexLib();
        }

        case 'd' | 'D' => {
            println("Enter HEX string to decode.");                             // Decode from HEX
            print("Separate values with commas and/or spaces.\n> ");
            try {
                println("= " + decodeHex(Console.in.readLine()) + "\n");
            } catch {
                case e : NumberFormatException => {                             // If user enters invalid
                    println("Please enter valid hexadecimal, and use " +        // string, give error and retry.
                            "only commas and spaces " +
                            "to separate each value.\n");
                }
                case x : Exception => {
                    System.err.println(x.getMessage);                           // If there's some other error, print
                    System.exit(1);                                             // message and quit w/ error code 1.
                }
            } finally { HexLib(); }
        }

        case 'q' | 'Q' => {                                                     // Quit program
            System.exit(0);
        }

        case _ => {                                                             // If other selection is made,
            println("Please enter a valid command.\n");                         // give error message.
            HexLib();
        }
    }
}                                                                               // :]