[bradhe]

Hey there, I'm an engineer on Relay. Our PM is busy so thought I'd jump in here.

Great question on why we went with YAML instead of our own DSL. The main reason is, really, YAML has become a bit lingua franca for managing configuration of tools similar to Relay. We wanted to keep Relay simple and make it as familiar as possible. So YAML was our go-to choice.

We have some control flow primitives that you can configure but to do really complicated logic we figured it's best to push that in to the steps versus the configuration (there by keeping the configuration simple). Here's a link to our (very simple) conditional execution docs: https://relay.sh/docs/using-workflows/conditionals/