Seems like a riff on the famous Perl Compatible Regular Expressions library (http://www.pcre.org), which is used in a bunch of high-profile things (PHP, and Apache Server, for starters). Kind of like "less" vs "more".

So a bit of an inside joke I guess, but most people familiar with regexes will probably have heard of PCRE, so it's not a terribly obscure reference. I liked it :)

PCRE is a set of extensions to RE to enable parsing of nonregular grammars. This is just RE. It's like calling some hypothetical language C++--. It doesn't make sense.

Well, if I designed a language that was C++ but stripped of some specific features for a purpose that made it less than C++, but still not quite just C, I might call it C++-- as a joke. In that respect, I think it makes perfect sense.

"Perl Compatible Regex" (pcre.org) is a popular regex library. The name PIRE is presumably a reference to that.

woosh

There's nothing wrong with it. Its implementation however is optimized for some use cases and not others. It appears that the folks at Yandex did not feel that crawling the web at their scale was one among the tasks for which it was suited.