### Add apt-repository, install ghc and cabal
I used [this](https://launchpad.net/~hvr/+archive/ghc) repository.
```bash
sudo add-apt-repository ppa:hvr/ghc
sudo apt-get install ghc-7.8.3
sudo apt-get install cabal-install-1.20
```

### Add the bin directory to PATH
The packages install into /opt/ghc/$VER and /opt/cabal/$VER respectively. If you use zsh, make sure to add to bash settings as well. In Emacs haskell-mode, when hasekll-interactive-bring command tries to load ghci, the PATH envrionment seems to be under bash. Save the settings and test.
```bash
source .zshrc
source .bashrc
which ghci
which cabal
```