Use Erlang Code From Hamler

Since Hamler compiles to CoreErlang, it makes sense that there should be some feature that allows you to call Erlang code from Hamler. This is a brief introduction to using Erlang code from Hamler. The FFI is a powerful feature, so you have to know what you are doing. One thing to keep in mind that though you can type foreign functions, Hamler has no way to check whether you have given the right type signature, so be careful and remember to keep impure code wrapped in IO.