As someone who is interesting in writing more Haskell, I've heard all the "if I get it to compile it works perfectly the first time", and I wonder if people are missing out on what proper TDD can bring them.

At first TDD becomes a way to assert your code does what you expect. After a few years you begin to use it as a design technique, and the correctness argument becomes less and less of a reason for using it. It's more of an (albeit nice) side effect at that point. I can write code that I test after the fact and still get the same correctness benefits, but the feedback I get from testing my design is gone.

Maybe I'm missing something, but I don't know if just having an excellent type checker is enough to provide the same quality feedback loop as well executed TDD does.