There is also the Cardano ecosystem which is mainly built on Haskell and runs one of the biggest and most active blockchains ever.

Hmm and there is a lot of discussion about it being a barrier to adoption.

I think it is a good tech choice to be honest, I want my blockchain carefully built and audited.

They also have a consistent history of wildly missing delivery dates though.

You mean, Haxl? [1] But AFAIK only a few devs are involved for the development.

[1] https://github.com/facebook/Haxl

No, their SPAM filter is (yes, still) in Haskell.

https://engineering.fb.com/2015/06/26/security/fighting-spam...

(For context: the spam filter uses the Haxl library. Yes Haxl itself has few developers; but it has many users)

Testament to how powerful Haskell can be :)

I’ve seen a small team of functional programmers tackle projects that would require dozens of OOP programmers. The challenge is finding them!

I imagine that is at least as much a feature of the type of programmers that self select to become "functional programmers" as it is a feature of the inherent advantage of function programming.

I worked with a guy who was an serious Lisp-hacker who could do fantastic things in Lisp and was always advocating that we do certain things in Lisp. But he was also a great programmer when 'forced' to use C++ or Perl, he just grumbled more while programming.

C++ and Perl are bad examples here. They are really expressive languages. I’d like to see the same developer using Go or Java 8.

At the risk of exposing myself, I’ve had to jump in and make changes to Sigma on several occasions. It was painful and I am not convinced having it in Haskell did anyone a favor.