feat(std/wasi): add wasi_snapshot_preview1 (denoland/deno#6441)

Author: caspervonb

wasi/README.md

@@ -0,0 +1,42 @@
+# wasi
+
+This module provides an implementation of the WebAssembly System Interface
+
+## Supported Syscalls
+
+## Usage
+
+```typescript
+import WASI from "https://deno.land/std/wasi/snapshot_preview1.ts";
+
+const wasi = new WASI({
+  args: Deno.args,
+  env: Deno.env,
+});
+
+const binary = Deno.readAll("path/to/your/module.wasm");
+const module = await WebAssembly.compile(binary);
+const instance = await WebAssembly.instantiate(module, {
+  wasi_snapshot_preview1: wasi.exports,
+});
+
+wasi.memory = module.exports.memory;
+
+if (module.exports._start) {
+  instance.exports._start();
+} else if (module.exports._initialize) {
+  instance.exports._initialize();
+} else {
+  throw new Error("No entry point found");
+}
+```
+
+## Testing
+
+The test suite for this module spawns rustc processes to compile various example
+Rust programs. You must have wasm targets enabled:
+
+```
+rustup target add wasm32-wasi
+rustup target add wasm32-unknown-unknown
+```