learnhaskell/install.md

What are Haskell, GHC, and Cabal?

Haskell is a programming language as laid out in the reports, most recent one being in 2010. The report is available as the onlinereport.

GHC

GHC is the most popular way to work in the Haskell language. It includes a compiler, REPL (interpreter), package management, and other things besides.

Cabal

Cabal does project management and dependency resolution. It's how you'll install projects, typically into their own sandbox.

Cabal is equivalent to Ruby's Bundler, Python's pip, Node's NPM, Maven, etc. GHC manages packaging itself, Cabal chooses what versions to install.

Installing GHC & Cabal

Ubuntu

This PPA is excellent and is what I use on all my Linux dev and build machines.

Specifically:

$ sudo apt-get update
$ sudo apt-get install python-software-properties # v12.04 and below
$ sudo apt-get install software-properties-common # v12.10 and above
$ sudo add-apt-repository -y ppa:hvr/ghc
$ sudo apt-get update
$ sudo apt-get install cabal-install-1.22 ghc-7.8.4 happy-1.19.5 alex-3.1.4

Then add the following to your $PATH (bash_profile, zshrc, bashrc, etc):

~/.cabal/bin:/opt/cabal/1.22/bin:/opt/ghc/7.8.4/bin:/opt/happy/1.19.5/bin:/opt/alex/3.1.4/bin

Optional: You could also add .cabal-sandbox/bin to your path. Code that you are actively developing will be available to you from the command line. This only works when your current working directory is a cabal sandbox.

Debian

Using Ubuntu PPA

If you're not using stable, you can follow the same steps as Ubuntu, but will have to execute an additional command. Immediately after sudo add-apt-repository -y ppa:hvr/ghc is executed run:

$ sudo sed -i s/jessie/trusty/g /etc/apt/sources.list.d/hvr-ghc-jessie.list

For other Debian versions, just replace all occurences of jessie with your version name in the command above.

If, for some reason, the file /etc/apt/sources.list.d/hvr-ghc-jessie.list does not exist, then /etc/apt/sources.list should contain a line like this:

deb http://ppa.launchpad.net/hvr/ghc/ubuntu jessie main

Replace jessie with trusty in this line.

Manual compilation

You can follow this guide written for Mac OS X:

Notes:

• Set your prefix accordingly when configuring ghc.
• Instead of grabbing the cabal-install binary, grab the source and then run bootstrap.sh script.

Fedora 21

To install Haskell 7.8.4 from the unofficial repo (Fedora 22+ will include it in the official one):

$ sudo yum-config-manager --add-repo \
> https://copr.fedoraproject.org/coprs/petersen/ghc-7.8.4/repo/fedora-21/petersen-ghc-7.8.4-fedora-21.repo
$ sudo yum install ghc cabal-install

As stated in petersen/ghc-7.8.4 copr page this ghc cannot be installed in parallel with Fedora/EPEL ghc.

Arch Linux

To install Haskell from the official repos on Arch Linux, run

$ sudo pacman -S cabal-install ghc happy alex haddock

Gentoo

On Gentoo, you can install the individual components of the Haskell Platform through Portage. If you use ACCEPT_KEYWORDS=arch (as opposed to ACCEPT_KEYWORDS=~arch), Portage will install ancient versions of the various Haskell things. With that in mind, iff you use ACCEPT_KEYWORDS=arch, add the following to /etc/portage/package.keywords.

dev-haskell/cabal-install
dev-lang/ghc

Once that is done,

$ emerge -jav dev-lang/ghc dev-haskell/cabal-install

Gentoo keeps a "stable" (read: old) version of cabal-install in the Portage tree, so you'll want to use cabal-install to install the more recent version. Note that the backslashes are intentional.

$ \cabal update                # The backslashes
$ \cabal install cabal-install # are intentional

You have now installed cabal on a global scale with portage, and locally in your home directory with cabal-install. The next step is to make sure that when you run cabal in a terminal, your shell will run the up-to-date version in your home directory. You will want to add the following lines to your shell's configuration file:

PATH=$PATH:$HOME/.cabal/bin
alias cabal="$HOME/.cabal/bin/cabal"

If you don't know what your shell is, more than likely, your shell is Bash. If you use Bash, the file you will edit is ~/.bashrc. If you use Z-shell, the file is ~/.zshrc. You can run the following command to find out what your shell is.

echo $SHELL | xargs basename

I use zsh, so that command outputs zsh when I run it.

Once you do all of that, you'll want to install the additional tools alex and happy.

$ cabal install alex happy

Congratulations! You now have a working Haskell installation!

Mac OS X

10.9

Install the GHC for Mac OS X app, which includes GHC and Cabal. It provides instructions on how to add GHC and Cabal to your path after you've dropped the .app somewhere.

10.6-10.8

Do the binary distribution install described below with this tarball.

Windows

• The windows minimal GHC installer is able to compile network et al. Technically in beta but should work for the purposes of anybody reading this guide.

Don't forget to run the installer as administrator as it will want to install in your Program Files.

Other Linux users

Download the latest binary distributions for cabal and ghc:

• GHC.

• Cabal.

Users of other Unix-like Systems

Install GHC and Cabal from your package system, then add ~/.cabal/bin to your $PATH. Finally update cabal and install the additional tools alex and happy.

$ cabal update
$ cabal install cabal-install alex happy