The ideal language for the AI has very short feedback loops with highly localized errors and minimal up front reasoning about types that itself provides a surface for flailing and errors. I'm not familiar enough with haskell to say for sure but I don't think this describes the language very well.
The ideal language for the engineer driving the agent has maximum comprehensibility, since review and understanding are the real bottlenecks now. I'm also pretty sure this doesn't describe haskell. It incompletely describes rust I think.
It does describe ocaml. And also gleam and maybe scala. And moonbit, developed by someone who is a proven expert in exactly this domain and explicitly targeting this problem space.
Yet, "short feedback loops with highly localized errors" is exactly what Haskell is. You can start Haskell in interpreter mode (ghci) and you get instant feedback. Errors are always localized. Although my experience with claude in the last few months shows that it rarely hits a compilation error at all.