Well, right now, I have:

When learning a programming language, usually the first example you are taught is how to print the statement "Hello, world!" to the screen. Regexes are a language unto themselves, so it's only fitting you see how to match a string containing the phrase, "Hello, world!":

  m/Hello, world!/
[download]

That was simple enough. But it requires some explaining; the / characters are the default regex delimiters. The m preceeding them is optional if you are using / as the delimiter. For now, we'll leave it in, but you should get used to seeing regexes without that leading m.

I'll work in some variant of what you've said. The preface is going to be like most prefaces, with some introductory text, followed by what you're expected to know, and "conventions used in this book".

japhy -- Perl and Regex Hacker