More features and examples

The parse dialect has a lot more useful features and functionalities. In this section, we discuss some more examples, so that you get a feeling for what is possible.

Using end

Remember our vowels example from The bitset! datatype section?

;-- see Chapter08/more-features.red:
vowel: charset"aeiou"
str: "dog"
find str vowel   ;== "og"

Using parse we can write this as follows:

parse str [ to vowel toend]    ;== true
parse"xyz" [ to vowel toend]  ;== false

The end word, which exists only in the parse dialect, returns true when the current position pointer is at the end of the input.

Building special languages

Email addresses are of the form host@domain, where domain is a "." followed by a three-letter domain name, and host can contain letters, digits, and one or more "-", such as [email protected].  We can build a pattern from the ground up to describe the components of an email pattern, like this:

digit: charset"0123456789"
letter: charset [#"a" - #"z" #"A" - #"Z"]
dash...