Rebol Programming/Language Features/Parse
PARSE is one of the most powerful features in Rebol. It has many capabilities from simple string splitting to parse expression matching. PARSE forms the basis of pattern matching in Rebol; in other languages pattern matching is often implemented as regular expression matching.
If you are asking yourself why Rebol has no regular expression matching implementation, PARSE is the answer.
A skeleton of a parsing operation:
parse INPUT RULE