I personally advise others that want to use this to just install GHCup via Haskell's official guideline in https://www.haskell.org/ghcup/install/
Remove "stack" dependency from the PKGBUILD file, then proceed with "makepkg -si"
GHCup will properly install the required versions, and the build will proceed correctly
Using Haskell Tool Stack from Arch's repo will just result in all sorts of headaches... I already tried.
