InvariantOps
A view of Stream that removes the variance from the type parameters. This allows
defining syntax in which the type parameters appear in contravariant (i.e. input)
position, which would fail to compile if defined as instance methods.
Value members
Concrete methods
Lifts this stream to the specified effect type.
Lifts this stream to the specified effect type.
- Example:
scala> import cats.effect.IO scala> Stream(1, 2, 3).covary[IO] res0: Stream[IO,Int] = Stream(..)
Synchronously sends values through p.
Synchronously sends values through p.
If p fails, then resulting stream will fail. If p halts the evaluation will halt too.
Note that observe will only output full chunks of O that are known to be successfully processed
by p. So if p terminates/fails in the middle of chunk processing, the chunk will not be available
in resulting stream.
Note that if your pipe can be represented by an O => F[Unit], evalTap will provide much greater performance.
- Example:
scala> import cats.effect.IO, cats.effect.unsafe.implicits.global scala> Stream(1, 2, 3).covary[IO].observe(_.printlns).map(_ + 1).compile.toVector.unsafeRunSync() res0: Vector[Int] = Vector(2, 3, 4)
Attaches to this stream an observer pipe, that pre-inspects the outputs
from this stream (the source) before the result stream emits them.
Attaches to this stream an observer pipe, that pre-inspects the outputs
from this stream (the source) before the result stream emits them.
Outputs from the source are fed to the observer pipe, to build a stream
that is run in the background. However, unlike the background method,
the observe method binds the mainstream: if the observation stream
reaches a stream end, the resulting stream is cut short.
The resulting stream emits the same outputs as the source (this) stream,
in the same order and chunk structure. However, no chunk is emitted by the
resulting stream until after the observer pipe is done processing it.
Any errors raised either from the evaluation of the source stream (this) or from the observer pipe (when applied to source chunks) will cause the termination of the resulting stream, and will be raised from this.
Observes this stream of Either[L, R] values with two pipes, one that
observes left values and another that observes right values.
Observes this stream of Either[L, R] values with two pipes, one that
observes left values and another that observes right values.
If either of left or right fails, then resulting stream will fail.
If either halts the evaluation will halt too.
Gets a projection of this stream that allows converting it to a Pull in a number of ways.
Gets a projection of this stream that allows converting it to a Pull in a number of ways.