FP Haskell Center
The rest of this page provides instructions for installing on your local system.
Stackage Server ensures you will get a set of packages that are known to compile together and run correctly, instead of needing to find a working package set yourself. This avoids the oft-sited "cabal hell" users have faced in the past.
If this is your first Haskell project, please use Stackage Server. The downside of this approach is that at the moment, all of your Haskell projects need to use Stackage server. This issue should be fixed soon, but if it is an issue for you, use the sandbox install instructions.
- Make sure your system is prepared to use Stackage Server, and then set up Stackage following the Getting Started section on the Stackage Server homepage.
- Install necessary build tools:
cabal install alex happy yesod-bin
You're now ready to start a new scaffolded site and build it:
yesod initand answer its questions to create a new scaffolded application
cdinto the newly created directory
- Install all library dependencies with
cabal install --enable-tests --reorder-goals --max-backjumps=-1 -j
- Note: This can take a while. On a fast computer, it will take around 10 minutes. On a slower system, it can take up to 40.
- Start up the devel server with
You've now got a running Yesod site at http://localhost:3000/.
Now it's time to start coding! You can play around with the code right now, or if you want to learn more, check out these resources:
Sandbox install Without Stackage Server
You are not required to use Stackage Server to install Yesod. If you would instead like to use regular Hackage, simply install your GHC and cabal-install as normal, and do not configure cabal to use a Stackage snapshot. Note that you will be more likely to run into dependency conflicts if you go this route.
You'll need two main tools: the Glasgow Haskell Compiler (GHC) and cabal-install, the package installer. The best way to get them is with the Haskell Platform.
If you're on Windows or Mac, download the installers from the Haskell Platform site. For Linux users, most distributions already include the platform in the repositories. On most Debian-based systems, for example, you can just run
sudo apt-get install haskell-platform
Make sure to add
$HOME/.cabal/bin to your
PATH. Once you're set up, run
to download a list of available packages. For more information on Haskell
tools, see the
tools chapter of the Mezzo Haskell book.
Mac users may also want to see
for help with their
Building Yesod and all of its dependencies is a simple procedure. Just run:
cabal update cabal install yesod-bin --max-backjumps=-1 --reorder-goals
Note that this will be installing a large number of packages, and may take a while. (15 minutes on modern systems, up to 40 minutes on older systems.) This is a one time setup, and will have no impact on normal development or runtime performance.
Start a new site
Now I'm sure you want to test this out! The
yesod executable has two important commands.
will ask you a few questions, and then generate a scaffolded site for you. At this point, you can follow the onscreen instructions to build and run your site. At the time of writing this page, the instructions are:
cabal sandbox init cabal install -j --enable-tests . yesod-platform yesod-bin --max-backjumps=-1 --reorder-goals yesod devel
which will set up a sandboxed environment, install all dependencies, and start the development server. After this is completed, you can access your site at http://localhost:3000/.
(Note: If the command line tool gives you different instructions, you should follow those instead.)