Object Future.Future

object Future

Future companion object.

Supertypes	class Object trait Matchable class Any
Self type	Future.type

Classlikes

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object never extends Future[Nothing]

A Future which is never completed.

Concrete methods

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final def apply[T](body: => T)(implicit executor: ExecutionContext): Future[T]

Starts an asynchronous computation and returns a Future instance with the result of that computation.

The following expressions are equivalent:

val f1 = Future(expr)
val f2 = Future.unit.map(_ => expr)
val f3 = Future.unit.transform(_ => Success(expr))

The result becomes available once the asynchronous computation is completed.

Type parameters	T the type of the result
Value parameters	body the asynchronous computation executor the execution context on which the future is run
Returns	the Future holding the result of the computation

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final def delegate[T](body: => Future[T])(implicit executor: ExecutionContext): Future[T]

Starts an asynchronous computation and returns a Future instance with the result of that computation once it completes.

The following expressions are semantically equivalent:

val f1 = Future(expr).flatten
val f2 = Future.delegate(expr)
val f3 = Future.unit.flatMap(_ => expr)

The result becomes available once the resulting Future of the asynchronous computation is completed.

Type parameters	T the type of the result
Value parameters	body the asynchronous computation, returning a Future executor the execution context on which the body is evaluated in
Returns	the Future holding the result of the computation

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final def failed[T](exception: Throwable): Future[T]

Creates an already completed Future with the specified exception.

Type parameters	T the type of the value in the future
Value parameters	exception the non-null instance of Throwable
Returns	the newly created Future instance

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final def find[T](futures: Iterable[Future[T]])(p: T => Boolean)(implicit executor: ExecutionContext): Future[Option[T]]

Asynchronously and non-blockingly returns a Future that will hold the optional result of the first Future with a result that matches the predicate, failed Futures will be ignored.

Type parameters	T the type of the value in the future
Value parameters	futures the scala.collection.immutable.Iterable of Futures to search p the predicate which indicates if it's a match
Returns	the Future holding the optional result of the search

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final def firstCompletedOf[T](futures: IterableOnce[Future[T]])(implicit executor: ExecutionContext): Future[T]

Asynchronously and non-blockingly returns a new Future to the result of the first future in the list that is completed. This means no matter if it is completed as a success or as a failure.

Type parameters	T the type of the value in the future
Value parameters	futures the IterableOnce of Futures in which to find the first completed
Returns	the Future holding the result of the future that is first to be completed

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final def foldLeft[T, R](futures: Iterable[Future[T]])(zero: R)(op: (R, T) => R)(implicit executor: ExecutionContext): Future[R]

A non-blocking, asynchronous left fold over the specified futures, with the start value of the given zero. The fold is performed asynchronously in left-to-right order as the futures become completed. The result will be the first failure of any of the futures, or any failure in the actual fold, or the result of the fold.

Example:

val futureSum = Future.foldLeft(futures)(0)(_ + _)

Type parameters	R the type of the value of the returned Future T the type of the value of the input Futures
Value parameters	futures the scala.collection.immutable.Iterable of Futures to be folded op the fold operation to be applied to the zero and futures zero the start value of the fold
Returns	the Future holding the result of the fold

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final def fromTry[T](result: Try[T]): Future[T]

Creates an already completed Future with the specified result or exception.

Type parameters	T the type of the value in the Future
Value parameters	result the result of the returned Future instance
Returns	the newly created Future instance

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final def reduceLeft[T, R >: T](futures: Iterable[Future[T]])(op: (R, T) => R)(implicit executor: ExecutionContext): Future[R]

Initiates a non-blocking, asynchronous, left reduction over the supplied futures where the zero is the result value of the first Future.

Example:

val futureSum = Future.reduceLeft(futures)(_ + _)

Type parameters	R the type of the value of the returned Future T the type of the value of the input Futures
Value parameters	futures the scala.collection.immutable.Iterable of Futures to be reduced op the reduce operation which is applied to the results of the futures
Returns	the Future holding the result of the reduce

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final def sequence[A, CC <: (IterableOnce), To](in: CC[Future[A]])(implicit bf: BuildFrom[CC[Future[A]], A, To], executor: ExecutionContext): Future[To]

Simple version of Future.traverse. Asynchronously and non-blockingly transforms, in essence, a IterableOnce[Future[A]] into a Future[IterableOnce[A]]. Useful for reducing many Futures into a single Future.

Type parameters	A the type of the value inside the Futures CC the type of the IterableOnce of Futures To the type of the resulting collection
Value parameters	in the IterableOnce of Futures which will be sequenced
Returns	the Future of the resulting collection

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final def successful[T](result: T): Future[T]

Creates an already completed Future with the specified result.

Type parameters	T the type of the value in the future
Value parameters	result the given successful value
Returns	the newly created Future instance

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final def traverse[A, B, M <: (IterableOnce)](in: M[A])(fn: A => Future[B])(implicit bf: BuildFrom[M[A], B, M[B]], executor: ExecutionContext): Future[M[B]]

Asynchronously and non-blockingly transforms a IterableOnce[A] into a Future[IterableOnce[B]] using the provided function A => Future[B]. This is useful for performing a parallel map. For example, to apply a function to all items of a list in parallel:

val myFutureList = Future.traverse(myList)(x => Future(myFunc(x)))

Type parameters	A the type of the value inside the Futures in the collection B the type of the value of the returned Future M the type of the collection of Futures
Value parameters	fn the function to be mapped over the collection to produce a collection of Futures in the collection to be mapped over with the provided function to produce a collection of Futures that is then sequenced into a Future collection
Returns	the Future of the collection of results

Concrete fields

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final val unit: Future[Unit]

A Future which is completed with the Unit value.