While I agree compile time is a big issue, I think the focus should really be on incremental build, because considering how much work the Haskell compiler has to do, it is expected to be quite slow on full build.

But incremental build has no reason to be slow, if the scope is as fine-grained as the function and type level.

It’s one of the reasons Tweag built rules_haskell for building Haskell with Bazel (and IIRC Buck2 too). Simon Marlow has also been talking recently about his work to build Haskell with Buck2, which he has on a fork of cabal-install.

(Disclaimer, I work at Tweag and recently did some work on the project)

I find initial build to be the most annoying, since it stops me from starting new projects in Haskell. It's also very annoying when setting up CI or switching machines or introducing new team members.