Galois makes some pretty cool stuff, and it's full of smart people. Buzzing through the slides I felt like it wasn't so much the case that Haskell was essential for building a business, but rather it was the right tool for the kinds of things Galois was looking to build, or maybe Galois picked doing those things because it was really good at Haskell (it is) and it just carried out a "hammer looking for nails" situation. I write in Haskell, yes, but I typically use it for specific things I'm trying to do (languages research, writing parsers, evaluating funky theoretical stuff). I'm not to keen to the idea of writing web pages in Haskell (<3's Rails) for example, or generally trying to shoehorn it into something that I would use C or Java for. The mental overhead just isn't there with the other language, especially for small projects where thinking of doing something with Monads would take me longer than just writing the thing in C and debugging it.<p>That being said, I think Haskell is an amazing language for what it's worth, and it's a great way for other language designers to see how many theoretical language features can be worked into a real life industry-grade language. Also, it's good for learning just because it's so different from everything else and can give you perspective on your programming.