That in itself sounds kinda dangerous. Not using some sort of "static" structure to define dependencies, I mean.

Actually the gemspec is simply a Ruby DSL that is used to generating a YAML-based definition file.

what like an interface? An API? That's what it is.

I more meant that a ruby program will be less predictable than a static XML file. Easier to reason about, mainly due to one being a list of dependencies, whereas the other is a turing machine.

Maybe. I think it's a difficult point to argue either way. It's a power vs discipline thing; with great power comes great responsibility. Some people prefer to be prevented from doing stupid things, and some people prefer the power.

I normally find that whenever you are limited to a certain config format etc, you find a use case that makes you wish the limitation wasn't there, so you jump through stupid hoops to get the same functionality.

Rails has a thing called fixtures, which is basically some static yaml files for loading test data into your database. It didn't take long at all for tools like factory girl to come out, which replace the yaml for ruby.

Maybe that's why a lot of people who are drawn to ruby are also drawn to lisp.