WIP investigation to build a Julia<->Rust interface

posts/rust-abi.md

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+---
+title: "Rust FFI to Julia"
+author: "Cristian Bourceanu"
+date: 2025-02-11T21:57:00Z
+categories: [rust, ffi, julia]
+---
+
+== WIP ==
+
+# Rust <-> Julia interface
+
+While I have grown to appreciate the differences in applications for these 2
+languages, these are not mutually exclusive and many times the stack or pipeline
+of components that compose one application might cross language boundaries.
+
+These might be because one language has much better support, usually in terms of
+libraries available, but also in robustness a complex library.
+
+While these 2 language are not truly compatible, some tricks can be added to
+ease translation, especially when it comes to the generics `Option` and `Result`
+in Rust. There are alternatives for these in Julia, even though by default Julia
+does not come equipped with the same paradigm:
+
+- [ResultTypes.jl](https://github.com/0x0f0f0f/ResultTypes.jl)
+- `Option` is generally used as `Union{T, Nothing}` in Julia
+
+
+## Rust ABI 
+
+There is currently no agreed way even for calling dylib Rust <-> Rust, known as
+an ABI, this is because the arguments are not assured to have any layout in
+memory, they are decided arbitrarily when compiled:
+
+[rust abi_stable crate](https://lib.rs/crates/abi_stable) 🤣:
+> the compiler is free to do whatever it pleases with these aspects of your
+> software: the process by which it does that is explicitly unstable, and
+> depends on your compiler version, the optimization level you selected, some
+> llama's mood in a wool farm near Berkshire... who knows?
+
+### Standard strategy: `extern "C"`
+
+The standard way to call Rust through a FFI is translating it into to expose a C
+interface and reuse the system C-ABI. This however causes to drop many of the
+guarantees Rust tries to make and induces a huge effort boundary of developing
+software that empowers these two languages to talk, since the translation effort
+is required two folds as boilerplate glueing code that doesn't add any
+value.
+
+## Interim solution to ease integration
+
+=> Develop `RustCall.jl` library similar to `PyCall.jl` which can use cargo
+packager to build Rust pacakge and generate the necessary C-FFI shims for the
+two sides as follows:
+
+1. Construct a SAT of the public interface of the Rust library
+2.