Flows-102

We haven’t covered the standard library yet, but for now, here are the basics: std is a globally available module, there to help you interact with the runtime.

You create flows using std.flow. It takes two parameters:

1. Name of the flow
2. An instance of a class

std.flow lets you go through the looking glass. It lets you provide a new state machine to the runtime, such that when it ticks, it manages this newly given state machine as well.

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FlowExecutor

A standard flow, lazily evaluated.

When you don’t provide a schedule to std.flow and call a FlowFunction, you get a FlowExecutor. This is a handle that encapsulates work.

A FlowExecutor doesn’t start its work unless explcitly told to do so. It has two function through which you can start execution:

interface FlowExecutor<RT, M> {
	run(): void;
	await(): RT;
}

Given a FlowExecutor is a handle, we can do this:

class Main {
	hello() {
		const flow = std.flow<Main>("Print!", this).world("Hello");
		this.print(flow); //We didn't call 'run' on flow, but gave it to 'print'.
	}

	world(arg: string) {
		std.log(`${arg} World!`);
	}

	// This takes a flow, and simply runs it.
	print(flow: std.FlowExecutor<void, Main['world']>) {
		flow.run();
	}
}

Try this code in the playground to see what happens!

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Scheduled Flows

A scheduled flow, eagerly evaluated, run immediately.

You can provide a schedule to std.flow to get a ScheduledFlow. A schedule is an object and it can have either of the following keys:

A ScheduledFlow is evaluated immediately, and it begins its work in the same tick it’s created.
Check out the playground to see how we can emulate a polling job using it.