Interop

Interop, or Interoperability is the capability to interact with other languages than the language you are using right now. It is often described as FFI, Foreign Function Interface. Is is an essential part of programming, to use libraries or code of other languages in your project. It makes sharing code much easier, the most popular language as a common denominator between multiple languages is the C programming language. It has evolved much more into a protocol than an actual language (in the context of FFI) over the years. Nearly all languages are able to interact with C code in a way, and Flint is no exception to that.

But Flint's approach to interop is much more generalized and not limited to C, as a matter of fact, you can call into any other language using Flint. There are, of course, limitations, especially around the topic of language-specifc constructs (traits in Rust, classes in C++, etc) but the benefits of a generalized interop approach are immense.

In this chapter, you will learn about the FIP, the Flint Interop Protocol, how to use it and how much power it gives you. You will not learn all the FIP internals in this chapter, though, that's a topic for a waaay later chapter. After this chapter, you will be able to call into external C code without any problem. I will not teach you the C programming language here, mind you, just how you can interact with it. But you do not need any prior knowledge in the C programming language for this chapter either, so don't worry, it will all be fine!