README.md

Rust allocation example

This example shows how to pass strings in and out of a Wasm function defined in Rust, built with cargo build --release --target wasm32-unknown-unknown

$ go run greet.go wazero
Hello, wazero!

Under the covers, lib.rs does a few things of interest:

• Uses a WebAssembly-tuned memory allocator: wee_alloc.
• Exports wrapper functions to allocate and deallocate memory.
• Uses &str instead of CString (NUL-terminated strings).
• Uses std::mem::forget to prevent Rust from eagerly freeing pointers returned.

Note: We chose to not use CString because it keeps the example similar to how you would track memory for arbitrary blobs. We also watched function signatures carefully as Rust compiles different WebAssembly signatures depending on the input type.

See https://wazero.io/languages/rust/ for more tips.