fs2 | 易学教程

why is my code not returning anything ? Scala fs2

阅读更多关于 why is my code not returning anything ? Scala fs2

问题 The program permits pushing Mapping Ints to Double and identifying the exit time from the queue. The program is not showing any error but It is not printing anything. What am I missing ? import cats.effect.{ExitCode, IO, IOApp, Timer} import fs2._ import fs2.concurrent.Queue import scala.concurrent.duration._ import scala.util.Random class Tst(q1: Queue[IO, (Double, IO[Long])])(implicit timer: Timer[IO]) { val streamData = Stream.emit(1) val scheduledStream = Stream.fixedDelay[IO](10.seconds)

why is my code not returning anything ? Scala fs2

阅读更多关于 why is my code not returning anything ? Scala fs2

How to group large stream into sub streams

阅读更多关于 How to group large stream into sub streams

问题 I want to group large Stream[F, A] into Stream[Stream[F, A]] with at most n element for inner stream. This is what I did, basically pipe chunks into Queue[F, Queue[F, Chunk[A]] , and then yields queue elements as result stream. implicit class StreamSyntax[F[_], A](s: Stream[F, A])( implicit F: Concurrent[F]) { def groupedPipe( lastQRef: Ref[F, Queue[F, Option[Chunk[A]]]], n: Int): Pipe[F, A, Stream[F, A]] = { in => val initQs = Queue.unbounded[F, Option[Queue[F, Option[Chunk[A]]]]].flatMap {

How to group large stream into sub streams

阅读更多关于 How to group large stream into sub streams

How can I Reuse a queue in another computation ? fs2 stream Scala

阅读更多关于 How can I Reuse a queue in another computation ? fs2 stream Scala

来源： https://stackoverflow.com/questions/62476044/how-can-i-reuse-a-queue-in-another-computation-fs2-stream-scala

C#中文件操作IO

阅读更多关于 C#中文件操作IO

StreamReader StreamReader sr = new StreamReader("qiufeng.txt", Encoding.GetEncoding("gb2312")); Console.WriteLine(sr.ReadLine()); Console.Wri /*--> */ /*--> */ teLine(sr.ReadLine()); 使用ReadLine()读取，每次读一行，并且每次读取的时候，从上次读取的下一行开始，并且，当文档读完的时候，返回空 string str2 = string.Empty; while ((str2 = sr.ReadLine()) != null) { Console.WriteLine(str2); } 读取文档的每一行。他和 string str3 = sr.ReadToEnd(); /*--> */ /*--> */ 是等价的。 WriteAllLines string[] str = { "山中相送罢，", "日暮掩柴扉。", "春草明年绿，", "王孙归不归。" }; File.WriteAllLines("qiufeng.txt", str); 会写入qiufeng.txt,并且如果原来文档中有数据会清空再增加 File.WriteAllText(@"D:\2.txt",sb.ToString()); /*-

FS2 Stream with StateT[IO, _, _], periodically dumping state

阅读更多关于 FS2 Stream with StateT[IO, _, _], periodically dumping state

问题 I have a program which consumes an infinite stream of data. Along the way I'd like to record some metrics, which form a monoid since they're just simple sums and averages. Periodically, I want to write out these metrics somewhere, clear them, and return to accumulating them. I have essentially: object Foo { type MetricsIO[A] = StateT[IO, MetricData, A] def recordMetric(m: MetricData): MetricsIO[Unit] = { StateT.modify(_.combine(m)) } def sendMetrics: MetricsIO[Unit] = { StateT.modifyF { s =>

Fs2 Stream.Compiler is not found (could not find implicit value Compiler[[x]F[x],G])

阅读更多关于 Fs2 Stream.Compiler is not found (could not find implicit value Compiler[[x]F[x],G])

问题 I am trying to compile the stream, but somehow Compiler is not in scope, what context bound is needed for bringing it in scope? import cats.Monad def compilingStream[F[_]: Monad]: F[List[Int]] = { val stream: fs2.Stream[F, Int] = fs2.Stream.emit(1).covary[F] stream.head.compile.toList } error: could not find implicit value for parameter compiler: fs2.Stream.Compiler[[x]F[x],G] stream.head.compile.toList ^ 回答1: Fs2 Stream#compile now requires a Sync[F] (see this): import cats.effect.Sync def

Mocking a method which returns an fs2.Stream

阅读更多关于 Mocking a method which returns an fs2.Stream

问题 Why isn't it possible to mock a method that returns an fs2.Stream with a Mockito mock? Mockito is complaining that I am trying to return a FreeC instead of a Stream. Why is that and how can I get it working? The following code: import cats.effect.IO import fs2.Stream import org.mockito.Mockito.when import org.scalatest.FlatSpec import org.scalatest.mockito.MockitoSugar trait MyTrait { def method: Stream[IO, Int] } class TestSpec extends FlatSpec with MockitoSugar { val m: MyTrait = mock