XXX add general installation instructions here
Installing on Linux/Unix
As far as we know there are currently no issues installing diagrams on Linux/Unix systems.
Installing on Windows
Cairo can unfortunately be difficult to install on Windows.
Here are instructions for installing gtk2hs on Windows. They work with the exception of the issue described here, which can be circumvented by passing the --global option to 'cabal install cairo' (if you don't mind installing cairo in the global package database).
Here is a discussion about the most recent difficulties.