Eh, I think I disagree with this. The point is that I can make very complicated libraries in Teal, and those compile down and are usable in lua scripts. This is where I actually used it - very simple scripts, very large and complicated library imported into those scripts. If you really need to prototype, just use lua, not teal. I've never found prototyping in teal to be a problem though.

On the other hand, I absolutely despise type annotations as comments. There is something so unclean about that - if I want a readable library, I want there to be type proofing all the way down. No switching between static and dynamic.