Before we start interfacing with Mathematica, we have to download the libraries and set up our system to do so. This is a little complicated. We'll need to download the library in order to handle the interoperability and move a few files around.
Part of what makes this task so difficult is that several things vary, depending on your operating system. Moreover, in order to work with Leiningen, this recipe uses some features of the underlying operating system that aren't available for Windows (symbolic links), so this recipe won't work for the Windows platform. However, Windows users can refer to the next recipe, Setting up Mathematica to talk to Clojuratica for Windows.