ToPull

Drops the first n elements of this Stream, and returns the new Stream.

Like dropWhile, but drops the first value which tests false.

Drops elements of the this stream until the predicate p fails, and returns the new stream. If defined, the first element of the returned stream will fail p.

Writes all inputs to the output of the returned Pull.

Reads a single element from the input and emits it to the output.

Reads the next available chunk from the input and emits it to the output.

Like [[unconsN]], but leaves the buffered input unconsumed.

Awaits the next available element where the predicate returns true.

Folds all inputs using an initial value z and supplied binary operator, and writes the final result to the output of the supplied Pull when the stream has no more values.

Folds all inputs using the supplied binary operator, and writes the final result to the output of the supplied Pull when the stream has no more values.

Writes a single true value if all input matches the predicate, false otherwise.

Takes the first value output by this stream and returns it in the result of a pull. If no value is output before the stream terminates, the pull is failed with a NoSuchElementException. If more than 1 value is output, everything beyond the first is ignored.

Returns the last element of the input, if non-empty.

Returns the last element of the input, if non-empty, otherwise fails the pull with a NoSuchElementException.

Like uncons but does not consume the chunk (i.e., the chunk is pushed back).

Like uncons1 but does not consume the element (i.e., the element is pushed back).

Like scan but f is applied to each chunk of the source stream. The resulting chunk is emitted while the resulting state is used in the next invocation of f. The final state value is returned as the result of the pull.

More general version of scanChunks where the current state (i.e., S) can be inspected to determine if another chunk should be pulled or if the pull should terminate. Termination is signaled by returning None from f. Otherwise, a function which consumes the next chunk is returned wrapped in Some. The final state value is returned as the result of the pull.

Like uncons, but instead of performing normal uncons, this will run the stream up to the first chunk available. Useful when zipping multiple streams (legs) into one stream. Assures that scopes are correctly held for each stream leg independently of scopes from other legs.

If you are not pulling from multiple streams, consider using uncons.

Emits the first n elements of the input.

Emits the last n elements of the input.

Like takeWhile, but emits the first value which tests false.

Emits the elements of the stream until the predicate p fails, and returns the remaining Stream. If non-empty, the returned stream will have a first element i for which p(i) is false.

Allows expressing Pull computations whose uncons can receive a user-controlled, resettable timeout. See Pull.Timed for more info on timed uncons and timeout.

As a quick example, let's write a timed pull which emits the string "late!" whenever a chunk of the stream is not emitted within 150 milliseconds:

Example

scala> import cats.effect.IO
scala> import cats.effect.unsafe.implicits.global
scala> import scala.concurrent.duration._
scala> val s = (Stream("elem") ++ Stream.sleep_[IO](200.millis)).repeat.take(3)
scala> s.pull
    |  .timed { timedPull =>
    |     def go(timedPull: Pull.Timed[IO, String]): Pull[IO, String, Unit] =
    |       timedPull.timeout(150.millis) >> // starts new timeout and stops the previous one
    |       timedPull.uncons.flatMap {
    |         case Some((Right(elems), next)) => Pull.output(elems) >> go(next)
    |         case Some((Left(_), next)) => Pull.output1("late!") >> go(next)
    |         case None => Pull.done
    |       }
    |     go(timedPull)
    |  }.stream.compile.toVector.unsafeRunSync()
res0: Vector[String] = Vector(elem, late!, elem, late!, elem)

For a more complex example, look at the implementation of Stream.groupWithin.

Waits for a chunk of elements to be available in the source stream. The ''non-empty''' chunk of elements along with a new stream are provided as the resource of the returned pull. The new stream can be used for subsequent operations, like awaiting again. A None is returned as the resource of the pull upon reaching the end of the stream.

Like uncons but waits for a single element instead of an entire chunk.

Like uncons, but returns a chunk of no more than n elements.

Pull.pure(None) is returned if the end of the source stream is reached.

Like uncons, but returns a chunk of exactly n elements, splitting chunk as necessary.

Pull.pure(None) is returned if the end of the source stream is reached.

ToPull

Value members

Concrete methods