garnet/rust/lib.rs
George Thomas 7bb41f6825 Call Rust from Haskell with cargo-cabal and hs-bindgen
See https://sraka.xyz/posts/hs-bindgen-introduction.html.

For now, this is a shell-based workflow, rather than using Nix to build everything, i.e. `nix develop` works but `nix build` doesn't. And `cargo build` has to be called manually to create the C library, rather than `cabal` being clever enough to invoke it itself.

We ran `cargo cabal init` from the `rust` directory (`nix shell github:yvan-sraka/cargo-cabal`), which generated `hsbindgen.toml` (which we use), and `Setup.lhs` (which just added `extra-lib-dirs`, and with the wrong paths, so we dspecify those statically instead in `garnet.cabal`). We also follow its advice to use `staticlib`.

Also, after we ran the first `cargo build` (requiring a `mkdir rust/src` before it would run), we took the generated the Haskell file, and moved the main contents in to `Main.hs` manually.
2026-02-19 13:57:14 +00:00

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Rust

use hs_bindgen::*;
#[hs_bindgen(hello :: CString -> IO (()))]
fn hello(name: &str) {
println!("Hello from Rust, {name}!");
}