A new chapter for the Nix language, courtesy of WebAssembly

Determinate Nix introduces experimental WebAssembly host calls. It lets Nix invoke Wasm modules, pass and return complex Nix values, and support Rust, C++, and Zig toolchains. It runs on Wasmtime/Cranelift and slashes runtime and memory: Fibonacci test 0.33s vs 79.33s, 30MB vs 4.5GB. Per-call instance overhead, however, limits throughput - about 123k calls/s vs 2.8M. Broadly, it shifts extensions away from C++ builtins or costly IFD toward portable, reproducible Wasm modules. That changes how Nix grows functionality.