None of my Manjaro or Arch Systems have any haskell or ghc packages installed.
It is certainly not essential for a Manjaro system. It can be removed, but it will also remove all packages hat require haskell.
Pick one of the haskell packages and find out which packages require it.
You can use
pacman -Qi package-name
or something like
pactree -r package-name
Maybe do it for a few to find out exactly which packages needs it. After that you can decide if you want to remove them all together or not.