If you were asked to make an e-commerce website in 2025, what language would you reach for? Show of hands: JavaScript? Go? Pascal? Well, there was at least one taker for that last one: [jns], and he has an hour-long tutorial video showing you how he made it happen.
Well that wasn’t meant to be too serious. You are surely aware of the situation that Haskell is not often used language in production. And a huge project you are doing with lot of Haskell is definitely something special.
Oh for sure, it’s definitely less common, though there are a number of other companies running it in production as well. This isn’t my first Haskell job, after all. My last job was also a similar size company and codebase. Facebook was even running it for a while for their sizeable abusive content detection system before that was shuttered due to company politics/policies (back when they were trying to do something about it at all).
But yeah, it’s not the first pick for a lot of companies, though I tend to think of that as a simple mindshare/inertia explanation than anything inherent to the language/ecosystem.