Installing Elm on Ubuntu

These instructions are what I used to install Elm on Ubuntu 14.04 (Trusty Tahr) Your mileage may definitely vary. These instructions are written for a user named you.

Haskell

You will want to install the Haskell compiler and Cabal, the Common Architecture for Building Applications and Libraries:

you@localhost:~$ sudo apt-get install ghc cabal-install

For Ubuntu 14.04, the Haskell compiler (ghc) is sufficiently new, but cabal is not the latest and greatest version.

you@localhost:~$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 7.6.3
you@localhost:~$ cabal --version
cabal-install version 1.16.0.2

First, update the list of packages available to install:

you@localhost:~$ cabal update
Config file path source is default config file.
Config file /home/you/.cabal/config not found.
Writing default configuration to /home/you/.cabal/config
Downloading the latest package list from hackage.haskell.org

In order to make the latest version of cabal available to all users, install it to /usr/local:

you@localhost:~$ sudo cabal install cabal-install --prefix=/usr/local
much output which I won’t reproduce here
Installing executable(s) in /usr/local/bin
Installed cabal-install-1.20.3

Note: You may need to have the zlib1 package installed in order to build properly. On my system, the packages were zlib1g and zlib1g-dev.

After the install is finished, close your terminal, open it again, and check the version. If /usr/local/bin is on your $PATH before /usr/bin, you should get results like this:

you@localhost:~$ cabal --version
cabal-install version 1.20.0.3
using version 1.20.0.2 of the Cabal Library

Since you did the install with sudo, the $HOME/.cabal directory may have some files marked as owned by the root user. Fix this by doing the following (replacing you with your user name). Then, as yourself, again make sure you have the latest packages.

you@localhost:~$ sudo chown -R you:you /home/you/.cabal
you@localhost:~$ cabal update

git

You will also need the git version control system, as the build process downloads the source from github:

you@locatlhost:~$ sudo apt-get install git

nodejs

If you want to use the Elm REPL, you will need Node.js. On Ubuntu, you do this:

you@localhost:~$ sudo apt-get install nodejs

The interpreter on Ubuntu is called nodejs because there is already a package named node, which happens to be an Amateur Packet Radio Node program. Thus, you will have to let the REPL know this new name. In a file named ~/.bash_aliases, add this line:

elm-repl='elm-repl --interpreter=node-js'

To activate this alias without having to log out and log in again, do this:

you@localhost:~$ source ~/.bash_aliases

(If you don’t want to create the alias, you will have to type the --interpreter=nodejs every time you run the REPL. Your choice.)

Building Elm

Download the BuildFromSource.hs script from https://raw.githubusercontent.com/elm-lang/elm-platform/master/src/BuildFromSource.hs. Now, open a shell as the root user and check to see that /usr/local/bin is on the $PATH, because you will need the proper version of cabal.

you@localhost:~$ sudo -s
root@localhost:~# echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

If it isn’t there, do this command:

root@localhost!# export PATH=/usr/local/bin:$PATH

The following commands will create a directory named Elm-Platform and install the version of Elm found on github’s 0.14 branch; it presumes that the BuildFromSource.hs script is in your home directory:

root@localhost:~# cd /usr/local
root@localhost:/usr/local# runhaskell /home/you/BuildFromSource.hs 0.14

Now, you must add the correct directory to your $PATH. Edit your ~/.profile and add this line at the end:

PATH=$PATH:/usr/local/Elm-Platform/0.14/bin

You will have to log out and log in again for this to take effect.

Using Elm

At this point, try these commands to see that everything is installed correctly:

you@localhost:~$ elm-package --help
you@localhost:~$ elm-repl --help
you@localhost:~$ elm-make --help

Your First Project

Create a directory named project1 and cd into it:

you@localhost:~$ mkdir project1
you@localhost:~$ cd project1

Then create a file named project1.elm with these contents, using your favorite text editor:

import Text (..)
import Graphics.Element (..)
import Graphics.Collage (..)
import Color (..)

main : Element

main = collage 200 200 [
    filled (rgb 102 51 153) (circle 50),
    toForm (plainText "Elm")
    ]

Now build the project with output to a file named project1.html. The first time you build your project, elm-make will detect packages you need and ask you if you want them. You don’t get the question after the first build, unless you need other packages.

you@localhost:~/project1$ elm-make --output project1.html project1.elm
Some new packages are needed. Here is the upgrade plan.

Install:
    elm-lang/core 1.0.0

Do you approve of this plan? (y/n) y
Packages configured successfully!
Compiled 33 files                                                   
Successfully generated project1.html
you@localhost:~/project1$ ls
elm-package.json  elm-stuff  project1.elm  project1.html

As you see, the build process has created a directory elm-stuff that contains the files from elm-lang/core. It also creates a file elm-package-json that contains information about the proejct. Load the project1.html file into your browser, and you should see something like this:

Now explore the examples and documentation at the Elm web site and make really cool stuff!

Note: Installing on Fedora

The same sequence will work on Fedora 19 (the version on which I tested it); the only changes are to use yum instead of apt-get, and you do not need to put in the alias for elm-repl, as Fedora uses the name node for Node.js.