futures market hours – FREEBANDZ (@1future)

The function will return when any future finishes or is cancelled. Convenient shortcuts to returning an immediate future from a else block, when the result is already known. Return a set of not yet finished Task objects run by the loop.

future perfect tense – Future On Spotify

FUTUREReturns a new sequencing Future that behaves like catch, but also passes the original future, $f1, to any functions it invokes. If passed another Future instance, the passed instance will be cancelled when the original future is cancelled.

If the future is ready, returns the exception passed to the fail method or undef if the future completed successfully via the done method. Returns the number of callbacks removed, which is typically 1, unless a callback was added more than once.

After this method returns, subsequent calls to isDone() will always return true. Subsequent calls to isCancelled() will always return true if this method returned true. If the future is already cancelled, this request is ignored. If the future is already complete with a result or a failure, an exception is thrown.

If the future is not yet ready, adds a callback to be invoked when the future is ready, if it completes successfully. If the future completed successfully, invokes it immediately. If it failed or was cancelled, it is not invoked at all.

Requests that the future be cancelled, immediately marking it as ready. This will invoke all of the code blocks registered by on_cancel, in the reverse order. When called on a convergent future, all its component futures are also cancelled. It is not an error to attempt to cancel a future that is already complete or cancelled; it simply has no effect.

Normally there is no need to create Future objects at the application level code. See also Future::Utils which contains useful loop-constructing functions, to run a future-returning function repeatedly in a loop.

If successful, its result will be a concatenated list of the results of all its component futures, in corresponding order. If it fails, its failure will be that of the first component future that failed. To access each component future’s results individually, use done_futures.

Here, we create a promise and use its future method to obtain the Future that it completes. Then, we begin two asynchronous computations. The first does some computation, resulting in a value r, which is then used to complete the future f, by fulfilling the promise p. The second does some computation, and then reads the result r of the completed future f. Note that the consumer can obtain the result before the producer task is finished executing the continueDoingSomethingUnrelated() method.


Because the done method returns the future object itself, it can be used to generate a Future that is immediately ready with a result. This can also be used as a class method. A Future is done if it was cancelled or if it has a result or an exception set with set_result() or set_exception() calls.

Note that FutureT is a type which denotes future objects, whereas Future.apply is a method which creates and schedules an asynchronous computation, and then returns a future object which will be completed with the result of that computation.

except that if the code throws an exception, it is wrapped in a new immediate fail future. If the return value from the code is not a blessed Future reference, an immediate fail future is returned instead to complain about this fact.

By default, futures and promises are non-blocking, making use of callbacks instead of typical blocking operations. To simplify the use of callbacks both syntactically and conceptually, Scala provides combinators such as flatMap, foreach, and filter used to compose futures in a non-blocking way. Blocking is still possible – for cases where it is absolutely necessary, futures can be blocked on (although this is discouraged).

Event loops use cooperative scheduling: an event loop runs one Task at a time. While a Task awaits for the completion of a Future, the event loop runs other Tasks, callbacks, or performs IO operations.

Returns a new sequencing Future that behaves like an else call which dispatches to a choice of several alternative handling functions depending on the kind of failure that occurred. If $f1 fails with a category name (i.e. the second argument to the fail call) which exactly matches one of the string names given, then the corresponding code is invoked, being passed the same arguments as a plain else call would take, and is expected to return a Future in the same way.


A Future represents the result of an asynchronous computation. Methods are provided to check if the computation is complete, to wait for its completion, and to retrieve the result of the computation. The result can only be retrieved using method get when the computation has completed, blocking if necessary until it is ready. Cancellation is performed by the cancel method. Additional methods are provided to determine if the task completed normally or was cancelled. Once a computation has completed, the computation cannot be cancelled. If you would like to use a Future for the sake of cancellability but not provide a usable result, you can declare types of the form Future and return null as a result of the underlying task.

To cancel a running Task use the cancel() method. Calling it will cause the Task to throw a CancelledError exception into the wrapped coroutine. If a coroutine is awaiting on a Future object during cancellation, the Future object will be cancelled.


We start by creating a future rateQuote which gets the current exchange rate. After this value is obtained from the server and the future successfully completed, the computation proceeds in the foreach callback and we are ready to decide whether to buy or not. We therefore create another future purchase which makes a decision to buy only if it’s profitable to do so, and then sends a request. Finally, once the purchase is completed, we print a notification message to the standard output.

If both tracing timestamps are defined, returns the number of seconds of elapsed time between them as a floating-point number. If not, returns undef. Promises can also be completed with a complete method which takes a potential value TryT- either a failed result of type FailureThrowable or a successful result of type SuccessT.

Other futures represent a collection of sub-tasks, and are implicitly marked as ready depending on the readiness of their component futures as required. These are called “convergent” futures here as they converge control and data-flow back into one place. These are the ones returned by the various wait_ and need_ constructors.

After this method returns, subsequent calls to isDone() will always return true. Subsequent calls to isCancelled() will always return true if this method returned true. If the future is already cancelled, this request is ignored. If the future is already complete with a result or a failure, an exception is thrown.

Requests that the future be cancelled, immediately marking it as ready. This will invoke all of the code blocks registered by on_cancel, in the reverse order. When called on a convergent future, all its component futures are also cancelled. It is not an error to attempt to cancel a future that is already complete or cancelled; it simply has no effect.

One nice property of programs written using promises with operations described so far and futures which are composed through monadic operations without side-effects is that these programs are deterministic. Deterministic here means that, given that no exception is thrown in the program, the result of the program (values observed in the futures) will always be the same, regardless of the execution schedule of the parallel program.

Returns a new Future instance that will indicate it is ready once all of the sub future objects given to it indicate that they have completed successfully, or when any of them indicates that they have failed. If any sub future fails, then this will fail immediately, and the remaining subs not yet ready will be cancelled. Any component futures that are cancelled will cause an immediate failure of the result.

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