Odomontois

package healer.reactive

import java.util.concurrent.atomic.{AtomicBoolean, AtomicReference}

import cats.effect.Concurrent
import cats.syntax.foldable._
import cats.syntax.monoid._
import cats.{Monad, Monoid}
import healer.reactive.impl._
import io.iteratee.Enumerator

Odomontois

Поясняю за Mid по запросу @aleksei_t

Исходная мысль была такая. Итак у нас есть

trait MyBusinessModule[F[_]]{
  def doBusinessThing(entity: Entity, info: Info): F[Value]
  def undoBusinessThing(entity: Entity): F[Respect]
}

LMnet

import cats.Applicative
import cats.data.NonEmptyList
import cats.effect.Concurrent
import cats.effect.concurrent.{Deferred, Ref}
import cats.implicits._
import fs2.concurrent.{InspectableQueue, SignallingRef}
import fs2.{Chunk, CompositeFailure, Scope, Stream}

object StreamPriorityUtils {

kwark

import cats.implicits._
import cats.effect.ExitCase.{Completed, Error}
import cats.effect.{ExitCode, IO, IOApp}
import cats.effect.concurrent.Ref
import eu.timepit.refined.api.{Refined, RefinedTypeOps}
import eu.timepit.refined.numeric.Interval
import eu.timepit.refined.W
import eu.timepit.refined.types.numeric.PosInt
import fs2.concurrent.Queue

danilbykov

import cats.effect.ExitCase._
import cats.effect.Sync
import cats.effect.concurrent.Ref
import cats.syntax.flatMap._
import cats.syntax.functor._

trait Tap[F[_]] {
  def apply[A](effect: F[A]): F[A]
}

jpsoroulas

Debezium installation

d1egoaz

If you want to learn Scala, I’d suggest:

• Install IntelliJ + Scala Plugin
• Don’t do the Coursera courses yet.
• Don’t do the “red book” Functional Programming in Scala yet.
• Do: http://underscore.io/books/
  • Essential Scala
  • Essential Play
  • Essential Slick
• Do Scala for the Impatient: https://www.amazon.com/Scala-Impatient-Cay-S-Horstmann/dp/0321774094
• The Neophyte’s Guide to Scala http://danielwestheide.com/scala/neophytes.html

mtesseract

The Problem

Defining records in Haskell causes accessor functions for the record's fields to be defined. There is no seperate namespace for these accessor functions.

The Goal

Be able to

• use records in Haskell, which share field names.
• use lenses for accessing these fields

aappddeevv

Scala and Cake Patterns and the Problem

Standard design patterns in scala recommend the cake pattern to help compose larger programs from smaller ones. Generally, for simple cake layers, this works okay. Boner's article suggests using it to compose repository and service layers and his focus is on DI-type composition. As you abstract more of your IO layers however, you realize that you the cake pattern as described does not abstract easily and usage becomes challenging. As the dependencies mount, you create mixin traits that express those dependence and perhaps they use self-types to ensure they are mixed in correctly.

Then at the end of the world, you have to mix in many different traits to get all the components. In addition, perhaps you have used existential types and now you must have a val/object somewhere (i.e. a well defined path) in order to import the types within the service so you can write your program. Existential

chanks

Turning PostgreSQL into a queue serving 10,000 jobs per second

RDBMS-based job queues have been criticized recently for being unable to handle heavy loads. And they deserve it, to some extent, because the queries used to safely lock a job have been pretty hairy. SELECT FOR UPDATE followed by an UPDATE works fine at first, but then you add more workers, and each is trying to SELECT FOR UPDATE the same row (and maybe throwing NOWAIT in there, then catching the errors and retrying), and things slow down.

On top of that, they have to actually update the row to mark it as locked, so the rest of your workers are sitting there waiting while one of them propagates its lock to disk (and the disks of however many servers you're replicating to). QueueClassic got some mileage out of the novel idea of randomly picking a row near the front of the queue to lock, but I can't still seem to get more than an an extra few hundred jobs per second out of it under heavy load.

So, many developers have started going straight t