Roto is a statically-typed and compiled scripting language for Rust applications that integrates very tightly with Rust. To achieve that integration, it needs to interface directly with Rust types and functions. Implementing that boundary turned out to be quite tricky! We had many obstacles to overcome, such as Rust providing very few mechanisms for reflection and not providing a stable ABI by default. This talk will explain how Rust-Roto boundary works and the tricks we have to pull along the way. You can expect lots of unsafe code, deep dives into the Rust Reference and coercions from slices to function pointers.