Webassembly Intro

Motivation

C / C++ / Rust / C# / Go / … now:
- …in your browser (near-native speed)
- …fully sandboxed on your server
  - FaaS: WasmEdge
- …embedded into your application
  - wasmer, wasmtime
Compilation Target
progenitor demo

How?

Binary .wasm modules: think DLL / shared object
no strings(!) / objects / stdlib / malloc / GC
Secure, sandboxed, type-checked function calls
Wasmer Python example
zero-copy memory access

Tools and APIs

Rust: wasm-bindgen (generate JS wrappers, npm module)
- js-sys: wrap javascript APIs
- js-web: wrap browser APIs
More tools for different targets
- e.g. WASI (filesystem / OS calls)
JS Object / DOM access:
- Nope. (call a JS wrapper…)
- May change… (reference types)

The Ugly

direct memory access (lifetime)
bleeding edge
- two(!) vite plugins needed
- vite optimized away module initialization (wasm-pack bug)
JS needed
size surprise
- shipping: fmt / malloc / hashmap / …
debugging… (ugh)
threads (webworker… getting better…)
Safari (slow)

Further Reading

MDN: WebAssembly Guides