I think the problem here is confusion, and I see it a lot in the Ansible community.

What you're doing, and I can completely understand why, is taking Ansible as being a programming language for defining state. That isn't what Ansible is designed to be.

That YAML you speak of is designed to allow you to define state in a format that is not only human readable, but also machine readable. All that YAML is meant to do is say: x=y. it's not trying to be a programming language or a scripting interface, it's simply a means of setting the state you want.

This is a common pitfall a lot of people fall into when they approach Ansible, and I'm always seeing questions on IRC like: "How do I code Ansible to pull down a file, read it, process it, and after doing some logic, do X?" The answer is: you're using Ansible wrong. Use it as a state management system and only a state management system, and you won't go wrong.

Use a scripting or programming language, write a script/program, and run that on the remote machine if you need highly complex logic to determine state.