Haskell isn't a pure "research-only" language. I realize people like to point out that it's original goal was research... however the nature of that research has changed over time. Take Galois' Crucible project where they used advanced dependent-types in order to write their security analysis tool [0]. They could have used research-grade dependently-typed languages that are much more expressive and easier to use... but they chose Haskell because they needed an industrial-grade compiler capable of producing fast code to run in a production setting. The kind of research being done in GHC and Haskell these days is bringing innovation and advancement in functional programming into industrial applications.

Every compiler is going to have warts. Especially with people using it and depending on it for industrial use. That's a good thing. You could be like Lean 4 which will make no promises of backwards compatibility or consideration for industrial users in the name of staying purely for research.

Although I agree that Haskell is impressive in its ability to evolve and grow! Linear types just landed in GHC 9.0.1 and many fine folks are improving the compiler to make way for dependent types. It's good stuff!

And to see languages like Java, C#, C++, and others pick up on the low-hanging fruit of FP languages is a sign that the paradigm is gaining popularity and adoption: ADTs, lamdbas, type inference, pattern matching... Maybe in 20-30 years will see these languages adopting higher-kinded types, rank-n types, GADTs, and more?

[0] https://www.researchgate.net/publication/334751646_Dependent...