Thank you Quinn for the explanation! Where I was trying to go with this is to use Swift Concurrency to get a similar in-order behavior for closure execution as an old pattern I'd use with Grand Central Dispatch using a semaphore. A sketch from memory: final class GCDSingleOperationRunner { let serialQueue = DispatchQueue(label: "singleOperationRunner.queue") typealias OperationAction = (_ completion: @escaping () -> ()) -> () func run(operation: @escaping OperationAction) { serialQueue.async { let semaphore = DispatchSemaphore(value: 0) operation { semaphore.signal() } semaphore.wait() } } } which would take in asynchronous methods with a completion handler: func syncWithRemote(completion: () -> Void) -> Void { fetchDataFromNetwork { data in writeToLocalDatabase(data) { completion() } } } singleOperationRunner.run(operation: syncWithRemote) singleOperationRunner.run(operation: syncWithRemote)