> They mention plentiful motivated job applications

I'd take anything from an advocacy article with a grain of salt.

> how is the market from the perspective of a developer looking to focus on Haskell?

Considering the only response you got points you to a subreddit, I'm guessing it isn't so great. At best, it is a niche market ( though that could be lucrative ).

I wouldn't put all my eggs in one basket. I'd make sure you have some expertise in Java, C#, C++, Python, etc ( don't forget SQL ) where there is a large established market that isn't going anywhere soon. But even more important, get experience in specific technologies ( databases , web servers, IDEs, version control, etc ).