Questions

1. Make a bitset to store all lowercase letters and another for all uppercase letters.
2. Use union to make a bitset storing all alphanumerical characters.
3. Use union to make a bitset storing all characters used in hexadecimal numbers.
4. Make a rules pattern integer to match with integer numbers, starting optionally with a + or - sign.
5. Make a pattern that matches the following product codes: "#ABC-nnnn" or "#XYZ-nnnn", where nnnn is a four-digit pattern.
6. Try for yourself to parse the data string to extract the exchange rate 0.81191502. (Hint: use some and the letter charset.)
7. Starting with rate: "<title>1 USD = 0.81191502 EUR</title>", change both tags to <rate> tags, by using two rules.
8. Use parse and the code within it to obtain the exchange rate info in this form: [ "EUR" 0.81191502 "GPB" 0.70675954 ......