--- /dev/null
+declare module 'wasi' {
+ interface WASIOptions {
+ /**
+ * An array of strings that the WebAssembly application will
+ * see as command line arguments. The first argument is the virtual path to the
+ * WASI command itself.
+ */
+ args?: string[];
+
+ /**
+ * An object similar to `process.env` that the WebAssembly
+ * application will see as its environment.
+ */
+ env?: object;
+
+ /**
+ * This object represents the WebAssembly application's
+ * sandbox directory structure. The string keys of `preopens` are treated as
+ * directories within the sandbox. The corresponding values in `preopens` are
+ * the real paths to those directories on the host machine.
+ */
+ preopens?: NodeJS.Dict<string>;
+
+ /**
+ * By default, WASI applications terminate the Node.js
+ * process via the `__wasi_proc_exit()` function. Setting this option to `true`
+ * causes `wasi.start()` to return the exit code rather than terminate the
+ * process.
+ * @default false
+ */
+ returnOnExit?: boolean;
+ }
+
+ class WASI {
+ constructor(options?: WASIOptions);
+ /**
+ *
+ * Attempt to begin execution of `instance` by invoking its `_start()` export.
+ * If `instance` does not contain a `_start()` export, then `start()` attempts to
+ * invoke the `__wasi_unstable_reactor_start()` export. If neither of those exports
+ * is present on `instance`, then `start()` does nothing.
+ *
+ * `start()` requires that `instance` exports a [`WebAssembly.Memory`][] named
+ * `memory`. If `instance` does not have a `memory` export an exception is thrown.
+ */
+ start(instance: object): void; // TODO: avoid DOM dependency until WASM moved to own lib.
+
+ /**
+ * Is an object that implements the WASI system call API. This object
+ * should be passed as the `wasi_snapshot_preview1` import during the instantiation of a
+ * [`WebAssembly.Instance`][].
+ */
+ readonly wasiImport: NodeJS.Dict<any>; // TODO: Narrow to DOM types
+ }
+}