Yi's performance has improved considerably. But it doesn't really do enough to use as your editor [ at least for me ]. I love xmonad; beautiful code and wonderful program. The Yi team seemed to aim for a great deal of the good things in Xmonad, but development slowed. I'm on Arch, but I find haskell programs -- it's my main language -- best with cabal. I.e. for you on Mint, I would just install your ghc package and your cabal-install package then install all other haskell programs with `cabal`. Now that it has sanboxing you may not need [ but certainly may use ] cabal_dev or hsv_env. I had a (the same?) gtk2hs error when using the arch packages for much of my haskell environment. Problem went away when moving to Cabal.
I think Yi could be spectacular ; especially as Haskell is so suited to language parsing. You could get things like what Emacs Semantic mode wants to be, only, um, actually work.
edit: i accendtly a word and there was some unwanted formatting