I know it is common to think that Haskell is used only in academia and side/weird-projects, but there is a decent amount of companies using Haskell - e.g. we use Haskell in production for developing a DSL / web framework for building web apps (https://github.com/wasp-lang/wasp)!
I participated teaching students Haskell on my alma mater this year and "what can Haskell be used for" was a common question, with genuine expectation that the answer will be it is limited to only specific use cases. I would answer that it can be used anywhere where languages like Java, C#, Go, and similar can be used -> it is a general programming language that uses garbage collector! And while somewhat harder to learn due to abstractions that we are all not used to, it is a delight to express business logic in it once you get to know it well.
The biggest factor for deciding if Haskell is a good fit for the problem is probably ecosystem support -> are there enough libraries and tools to support efficient development in a specific problem domain. In our case, we are building a compiler/transpiler, and Haskell is well-known for great support in that area, so it was a no-brainer. We were actually also considering Rust, but we just had no need for that level of memory control and rather decided to go with language where we don't have to think about that (Haskell).
> The biggest factor for deciding if Haskell is a good fit for the problem is probably ecosystem support
And hiring right, or being prepared to train/let new hires climb up a steeper learning curve than hiring someone with Python experience for a Ruby app say.
Rust has reached that critical mass I think, got past the chicken/egg issue of experienced people to hire & companies interested in hiring them (to work on a rust codebase). Against the odds I think, there are plenty of languages you hear about similarly up and coming that haven't (D, Zig) or have only in a niche (F#, Swift, Kotlin - the last two I include mainly because I'm thinking Go could so easily have gone the same way, just been the one Google pushed for K8s plugins and GAE applications, not used generally as it is despite being a general-purpose language).
Anecdotally, hiring Haskell developers seems far easier than you’d expect. There are a lot more people out there who want to use Haskell than there are Haskell jobs. Having some training is good- you don’t want to lose out on talented people because they haven’t used Haskell before, but it’s not like everything you know goes out the window when you learn Haskell either. With some help most people should be pretty proficient in a couple of months, and you can have people learn the language in parallel with learning the codebase and business domain, so you aren’t really losing that much time in practice.
I can confirm this! We had no problem getting a very decent number of applications for Haskell position, both from very experienced Haskell devs, and from junior Haskell devs, all very motivated.
As for getting somebody on-board -> we hired a couple senior / intermediate devs that had no or introductory knowledge of Haskell, and all of them so far got up to speed in a month or so, while not learning exclusively Haskell but also the rest of the codebase at the same time, so normal learning process in the new company. So I wouldn't say at all that learning Haskell for them was an issue, but I am certain that big factor here was that they are generally experienced in other languages. That said, we do keep our codebase pretty tidy and simple (no super crazy Haskell features).
I participated teaching students Haskell on my alma mater this year and "what can Haskell be used for" was a common question, with genuine expectation that the answer will be it is limited to only specific use cases. I would answer that it can be used anywhere where languages like Java, C#, Go, and similar can be used -> it is a general programming language that uses garbage collector! And while somewhat harder to learn due to abstractions that we are all not used to, it is a delight to express business logic in it once you get to know it well.
The biggest factor for deciding if Haskell is a good fit for the problem is probably ecosystem support -> are there enough libraries and tools to support efficient development in a specific problem domain. In our case, we are building a compiler/transpiler, and Haskell is well-known for great support in that area, so it was a no-brainer. We were actually also considering Rust, but we just had no need for that level of memory control and rather decided to go with language where we don't have to think about that (Haskell).