Comment by jfengel

It's not a DSL. It's a generic lexer and parser. It takes the text and gives you an abstract syntax tree. The actual DSL is your spec, and the syntax you apply.

It's one of many equivalent such parser tools, a particularly verbose one. As such it's best for stuff not written by hand, but it's ok for generated text.

It has some advantages mostly stemming from its ubiquity, so it has a big tool kit. It has a lot of (somewhat redundant) features, making it complex compared to other options, but sometimes one of those features really fits your use case.