That was "interesting" in that I like expanding my horizons, but it was a terrible presentation. Plus, it looks like Haskell and I got the impression from his lead-in that he was going to introduce a new language.
However, I actually came here to say something else about his material: if it is harder to decompose the business requirement into Haskell than it is to write monkey tests for one's Blub language, I am not certain anyone wins when going with a provably correct implementation.
My experience using advanced type system tells me that you can get away with functional tests. Types, also, takes much less code space-programmer's time than tests.
So I do not see how they could be harder to use. Certainly types will be unusual, but not much harder.
However, I actually came here to say something else about his material: if it is harder to decompose the business requirement into Haskell than it is to write monkey tests for one's Blub language, I am not certain anyone wins when going with a provably correct implementation.