notes on elm ffi hackery

ffi.elm

D.decodeValue
    (D.field "return" D.float)
    (En.object [ ( "__elm-js-ffi", En.list En.float [ 1, 2 ] ) ])

javascript.js

//note passing in an object under flags might be better than monkey patching the Object object
Object.defineProperty(Object.prototype, `__elm-js-ffi`, {
	set(args) {
		this.return = add(...args);
	}
});
function add(a, b) {
	return a + b;
}

const setTimeoutOld = setTimeout;
globalThis.setTimeout = (callback, time, ...args) => {
	if (time === -1) {
		const
			{ name
			, args
			} = JSInElm.nextTask;
		JSInElm.tasks[name](...args)
			.then(result => {
				JSInElm.taskResults[name] = result;
				callback();
			});
	} else {
		return setTimeoutOld(callback, time, ...args);
	}
}