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Relax constraint for Signal.constant #3032

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Relax constraint for Signal.constant #3032

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bfb3d42
Relax constraint for `Signal.constant`
armanbilge Oct 30, 2022
0fed440
Merge branch 'main' into pr/relax-signal-constant
armanbilge Dec 27, 2022
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7 changes: 5 additions & 2 deletions core/shared/src/main/scala/fs2/concurrent/Signal.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@ package fs2
package concurrent

import cats.data.OptionT
import cats.effect.kernel.{Concurrent, Deferred, Ref}
import cats.effect.kernel.{Concurrent, Deferred, Ref, Spawn}
import cats.effect.std.MapRef
import cats.syntax.all._
import cats.{Applicative, Functor, Invariant, Monad}
Expand Down Expand Up @@ -112,13 +112,16 @@ trait Signal[F[_], A] {
}

object Signal extends SignalInstances {
def constant[F[_], A](a: A)(implicit F: Concurrent[F]): Signal[F, A] =
def constant[F[_], A](a: A)(implicit F: Spawn[F]): Signal[F, A] =
new Signal[F, A] {
def get: F[A] = F.pure(a)
def continuous: Stream[Pure, A] = Stream.constant(a)
def discrete: Stream[F, A] = Stream(a) ++ Stream.never
}

@deprecated("Use overload with Spawn constraint", "3.4.0")
def constant[F[_], A](a: A, F: Concurrent[F]): Signal[F, A] = constant(a)(F)

def mapped[F[_]: Functor, A, B](fa: Signal[F, A])(f: A => B): Signal[F, B] =
new Signal[F, B] {
def continuous: Stream[F, B] = fa.continuous.map(f)
Expand Down