Mark Proctor has posted an interview he did with Terence Parr of ANTLR fame. Ter is one of the nicest and smartest guys I know.

Back in the day, teaching myself how to program in C++, I decided to write my own scripting language. I'd tried (f)lex/yacc/bison, and they were either not friendly to C++, or not friendly to the way my brain works. Then I stumbled across PCCTS and recursive-descent LL(k) parsers. For once, the grammar productions seemed to make sense. The generated code seemed to be readable and make sense.

Praise be unto Terence Parr, creator of PCCTS.

Then he abandoned C++ for Java, and created ANTLR. Now it's up to version 3.0. And has a book.

ANTLR is one of those libraries that you either love or have never heard about. You've probably enjoyed the benefits of ANTLR none-the-less.

• JBoss Rules rule language parsing
• Hibernate HQL parsing
• Groovy language parsing

Being able to create a parser for a new little language (or "DSL" to be hip and trendy) opens up a whole world when implementing new software. It makes it easy to think of formats beyond XML or CSV. Users get tired of being stabbed in the eye with XML's pointy brackets.