It is my experience with Haskell Arch packages, as the lack of forum feedback suggested to me, with my troubles with dependencies for pandoc or git-annex-bin,[0] to go and cabal it.[1] That is just me.
I know that goes against the point of this whole post, but I wanted to learn more about Haskell and part of that for me was leaving the farm and running wild, so to speak.
This is my experience as well, and the person who maintains "ghc/cabal-install/and the other haskell packages in [extra]" had a similar sentiment in a reddit thread[1] eight months ago.
Cabal is able to give you enough headaches on its own. :-)
I do love pacman and the Arch package database in most other regards, however.
I know that goes against the point of this whole post, but I wanted to learn more about Haskell and part of that for me was leaving the farm and running wild, so to speak.
[0] https://aur.archlinux.org/packages/haskell-setenv
[1]https://bbs.archlinux.org/viewtopic.php?id=173781