Haskell Ubuntu install

sudo apt-get install -y software-properties-common
sudo add-apt-repository ppa:hvr/ghc
sudo apt-get update
sudo apt-get install ghc-8.6.3
sudo apt-get install cabal-install-2.4


i.e.:
export PATH=/opt/ghc/8.0.2/bin/:$PATH
export PATH=/opt/ghc/bin/:$PATH

multiple ghc:
$ activate-hs
You must be root to activate a particular Haskell Platform.
Please rerun this command sudo:
    sudo /usr/local/bin/activate-hs