And composability lets you create business DSLs and macros on top of that. I've used this to good effect with Rails' Arel, but since it is still Ruby, you can't

And composability lets you create business DSLs and macros on top of that. I've used this to good effect with Rails' Arel, but since it is still Ruby, you can't go as far unless you're willing to parse the Ruby into something more legible, like S-expressions.