A workaround for long compile times is trying to stay withing GHCi whenever possible and reload from there.

http://chrisdone.com/posts/haskell-repl

http://chrisdone.com/posts/making-ghci-fast

The Haxl team seem to use this strategy:

"Haxl users at Facebook do a lot of development and testing inside GHCi. In fact, we’ve built a customized version of GHCi that runs code in our Haxl monad by default instead of the IO monad, and has a handful of extra commands to support common workflows needed by our developers."

http://simonmar.github.io/posts/2016-02-12-Stack-traces-in-G...