Well, the example you are looking at is very complex, but also you are very unlikely to run into it early! For better examples, look at the homepage: you will s

Well, the example you are looking at is very complex, but also you are very unlikely to run into it early! For better examples, look at the homepage: you will see something much more approachable. The reason this snippet is complex is that: 1. It deals with the Foreign Function Interface 2. It deals with the FFI with respect to C++, which is much more complex than the one towards C, essentially because C++ itself is complex 3. It uses a particular construct (emit) that is only needed when the standard FFI is not enough So the example is really a showcase of a particularly complex case that you will likely not encounter, unless you start wrapping C++ libraries (which is not an easy task, unlike the C ones)