Happstack is freely available under the BSD3 license.
The easiest way to get happstack is to just install it from hackage using the cabal command.
$ export PATH=~/.cabal/bin:$PATH $ cabal update $ cabal install happstack-server
You can get and install the latest development source using git.
$ git clone https://github.com/Happstack/happstack-server.git
After you have checked out the code, you can get further updates by running:
$ git pull
You can browse the source code online by visiting our github.