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Async / Await

mType supports asynchronous functions with Promise<T> values, scheduled cooperatively on the VM event loop.

async Functions​

Mark a function async to make it return a Promise<T>:

function async getMessage(): Promise<Message> {
    Message msg = new Message("Hello from async");
    return msg;
}

The return type is wrapped: from inside the function you return a Message; callers receive a Promise<Message>.

await​

Inside another async function, use await to suspend until a promise resolves:

function async testBasic(): Promise<Message> {
    Message result = await getMessage();
    return result;
}

A Complete Example​

function async getMessage(): Promise<Message> {
    Message msg = new Message("Hello from async");
    return msg;
}

function async testBasic(): Promise<Message> {
    Message result = await getMessage();
    return result;
}

function async main(): Promise<Message> {
    Message msg = await testBasic();
    print("Result: " + msg.getText());
    return msg;
}

Top-level main() may itself be async — the VM runs the event loop until the returned promise settles.

Concurrency Patterns​

Sequential​

A a = await stepA();
B b = await stepB(a);
return b;

Mixing Sync and Async​

A regular (non-async) function cannot use await directly. Wrap synchronous work in an async function or call the sync function before/after the await chain.

See Also​