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Merge pull request #39 from armanbilge/feature/signal-monad
Add `Monad[Signal]`
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| Original file line number | Diff line number | Diff line change |
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| /* | ||
| * Copyright 2022 Arman Bilge | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
|
|
||
| /* | ||
| * Copyright (c) 2013 Functional Streams for Scala | ||
| * | ||
| * Permission is hereby granted, free of charge, to any person obtaining a copy of | ||
| * this software and associated documentation files (the "Software"), to deal in | ||
| * the Software without restriction, including without limitation the rights to | ||
| * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of | ||
| * the Software, and to permit persons to whom the Software is furnished to do so, | ||
| * subject to the following conditions: | ||
| * | ||
| * The above copyright notice and this permission notice shall be included in all | ||
| * copies or substantial portions of the Software. | ||
| * | ||
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | ||
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS | ||
| * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR | ||
| * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER | ||
| * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN | ||
| * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. | ||
| */ | ||
|
|
||
| package calico | ||
| package frp | ||
|
|
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| import cats.Monad | ||
| import cats.StackSafeMonad | ||
| import cats.data.OptionT | ||
| import cats.effect.kernel.Concurrent | ||
| import cats.syntax.all.* | ||
| import fs2.Pull | ||
| import fs2.Stream | ||
| import fs2.concurrent.Signal | ||
|
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| given [F[_]: Concurrent]: Monad[Signal[F, _]] = new StackSafeMonad[Signal[F, _]]: | ||
| def pure[A](a: A) = Signal.constant(a) | ||
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|
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| override def map[A, B](siga: Signal[F, A])(f: A => B) = | ||
| Signal.mapped(siga)(f) | ||
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| def flatMap[A, B](siga: Signal[F, A])(f: A => Signal[F, B]) = new: | ||
| def get = siga.get.flatMap(f(_).get) | ||
| def continuous = Stream.repeatEval(get) | ||
| def discrete = siga.discrete.switchMap(f(_).discrete) | ||
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| override def ap[A, B](ff: Signal[F, A => B])(fa: Signal[F, A]) = | ||
| new: | ||
| def discrete: Stream[F, B] = | ||
| nondeterministicZip(ff.discrete, fa.discrete).map(_(_)) | ||
| def continuous: Stream[F, B] = Stream.repeatEval(get) | ||
| def get: F[B] = ff.get.ap(fa.get) | ||
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| private def nondeterministicZip[A0, A1]( | ||
| xs: Stream[F, A0], | ||
| ys: Stream[F, A1] | ||
| ): Stream[F, (A0, A1)] = | ||
| type PullOutput = (A0, A1, Stream[F, A0], Stream[F, A1]) | ||
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| val firstPull: OptionT[Pull[F, PullOutput, *], Unit] = for | ||
| firstXAndRestOfXs <- OptionT(xs.pull.uncons1.covaryOutput[PullOutput]) | ||
| (x, restOfXs) = firstXAndRestOfXs | ||
| firstYAndRestOfYs <- OptionT(ys.pull.uncons1.covaryOutput[PullOutput]) | ||
| (y, restOfYs) = firstYAndRestOfYs | ||
| _ <- OptionT.liftF { | ||
| Pull.output1[F, PullOutput]((x, y, restOfXs, restOfYs)): Pull[F, PullOutput, Unit] | ||
| } | ||
| yield () | ||
|
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| firstPull.value.void.stream.flatMap { (x, y, restOfXs, restOfYs) => | ||
| restOfXs.either(restOfYs).scan((x, y)) { | ||
| case ((_, rightElem), Left(newElem)) => (newElem, rightElem) | ||
| case ((leftElem, _), Right(newElem)) => (leftElem, newElem) | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,92 @@ | ||
| /* | ||
| * Copyright 2022 Arman Bilge | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
|
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| package calico.frp | ||
|
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| import cats.data.NonEmptyList | ||
| import cats.effect.IO | ||
| import cats.effect.kernel.Resource | ||
| import cats.effect.testkit.TestControl | ||
| import cats.effect.testkit.TestInstances | ||
| import cats.kernel.Eq | ||
| import cats.laws.discipline.ApplicativeTests | ||
| import cats.laws.discipline.MonadTests | ||
| import cats.syntax.all.* | ||
| import fs2.Stream | ||
| import fs2.concurrent.Signal | ||
| import fs2.concurrent.SignallingRef | ||
| import munit.DisciplineSuite | ||
| import org.scalacheck.Arbitrary | ||
| import org.scalacheck.Arbitrary.arbitrary | ||
| import org.scalacheck.Gen | ||
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| import scala.concurrent.duration.* | ||
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| class SignalSuite extends DisciplineSuite, TestInstances: | ||
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| override def scalaCheckTestParameters = | ||
| if sys.props("java.vm.name").contains("Scala.js") then | ||
| super.scalaCheckTestParameters.withMinSuccessfulTests(10).withMaxSize(10) | ||
| else super.scalaCheckTestParameters | ||
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| case class TestSignal[A](events: NonEmptyList[(FiniteDuration, A)]) extends Signal[IO, A]: | ||
| def discrete: Stream[IO, A] = Stream.eval(IO.realTime).flatMap { now => | ||
| def go(events: NonEmptyList[(FiniteDuration, A)]): (A, List[(FiniteDuration, A)]) = | ||
| events match | ||
| case NonEmptyList((_, a), Nil) => (a, Nil) | ||
| case NonEmptyList((t0, a0), tail @ ((t1, a1) :: _)) => | ||
| if t1 > now then (a0, tail) | ||
| else go(NonEmptyList.fromListUnsafe(tail)) | ||
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| val (current, remaining) = go(events) | ||
| Stream.emit(current) ++ Stream.emits(remaining).evalMap { (when, a) => | ||
| IO.realTime.map(when - _).flatMap(IO.sleep).as(a) | ||
| } | ||
| } | ||
| def get = IO.never | ||
| def continuous = Stream.never | ||
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| given [A: Arbitrary]: Arbitrary[Signal[IO, A]] = | ||
| given Arbitrary[FiniteDuration] = Arbitrary(Gen.posNum[Byte].map(_.toLong.millis)) | ||
| Arbitrary( | ||
| for | ||
| initial <- arbitrary[A] | ||
| tail <- arbitrary[List[(FiniteDuration, A)]] | ||
| events = tail.scanLeft(Duration.Zero -> initial) { | ||
| case ((prevTime, _), (sleep, a)) => | ||
| (prevTime + sleep) -> a | ||
| } | ||
| yield TestSignal(NonEmptyList.fromListUnsafe(events)) | ||
| ) | ||
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| given [A: Eq](using Eq[IO[List[(A, FiniteDuration)]]]): Eq[Signal[IO, A]] = Eq.by { sig => | ||
| IO.ref(List.empty[(A, FiniteDuration)]).flatMap { ref => | ||
| TestControl.executeEmbed( | ||
| sig | ||
| .discrete | ||
| .evalMap(IO.realTime.tupleLeft(_)) | ||
| .evalMap(x => ref.update(x :: _)) | ||
| .compile | ||
| .drain | ||
| .timeoutTo(Long.MaxValue.nanos, IO.unit) | ||
| ) *> ref.get.map(_.distinctBy(_._2)) | ||
| } | ||
| } | ||
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| given Ticker = Ticker() | ||
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| // it is stack-safe, but expensive to test | ||
| checkAll("Signal", MonadTests[Signal[IO, _]].stackUnsafeMonad[Int, Int, Int]) |
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