--[=[
	The same as [Promise.new](/api/Promise#new), except execution begins after the next `Heartbeat` event.

	This is a spiritual replacement for `spawn`, but it does not suffer from the same [issues](https://eryn.io/gist/3db84579866c099cdd5bb2ff37947cec) as `spawn`.

	```lua
	local function waitForChild(instance, childName, timeout)
	  return Promise.defer(function(resolve, reject)
		local child = instance:WaitForChild(childName, timeout)

		;(child and resolve or reject)(child)
	  end)
	end
	```

	@param executor (resolve: (...: any) -> (), reject: (...: any) -> (), onCancel: (abortHandler?: () -> ()) -> boolean) -> ()
	@return Promise
]=]

function Promise.defer(executor)
	local traceback = debug.traceback(nil, 2)
	local promise
	promise = Promise._new(traceback, function(resolve, reject, onCancel)
		local connection
		connection = Promise._timeEvent:Connect(function()
			connection:Disconnect()
			local ok, _, result = runExecutor(traceback, executor, resolve, reject, onCancel)

			if not ok then
				reject(result[1])
			end
		end)
	end)

	return promise
end
