> the chances of using it for more than toy scripts are slim

If you are proficient in Haskell and willing to relocate, I believe there are some amazing opportunities for you. You'll work with really smart people and be innovating. I see investment banks, startups and defense contractors using this language. Interesting mix.

> you'll find it a hard sell

So was Ruby at some point. But oh boy how much quicker was I writing those web apps in 2005 because of it!

> try to avoid code that requires your coworkers to know abstract algebra and category theory in order to contribute to a project

Good quote. But it does not "summarizes functional languages well" in my opinion. It shows that you should keep the clever stuff in libraries, such that colleagues do not have to trip over it.