Don't try to convince someone by trotting out a list of things you think make Perl cooler than other languages. Chances are good that the person who knows "other language" better than you will already know how to accomplish the same thing in a more "other-language-ish" way.
That's a good point. And if he really cared about regexes and glue language, he'd already be using Perl. The fact that he thinks one regex implementation is as good as another tells me that a list of Perl's strengths just isn't going to impress him. (The fact that he used "easy" and "Java" in the same sentence makes me think I wouldn't try.) Perl isn't a buzzword language; a lot of what makes it special is hard to define.
Take statement modifiers, for instance. At first glance, they may seem superfluous -- they don't let you do anything you couldn't already do with normal loops. But it's hard to describe how much they aid the process of reading and writing code (and how frustrating it is to switch to a language that doesn't have them). Similarly, it's hard to explain why =~s///g is so much better than preg_replace(), but it is. I think a lot of Perl is that way.
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