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Fibers

Fibers are an abstraction over sequential computation, similar to threads but at a higher level. There are two ways to think about this model: by example, and abstractly from first principles. We'll start with the example.

(credit here is very much due to Fabio Labella, who's incredible Scala World talk describes these ideas far better than I can)

Callback Sequentialization

Consider the following three functions

@jdegoes
jdegoes / zio-test.scala
Last active October 13, 2024 16:17
Simple example of testing with ZIO environment
object test {
import scalaz.zio._
type UserID = String
case class UserProfile(name: String)
// The database module:
trait Database {
val database: Database.Service
import cats.{ ApplicativeError, MonadError }
import cats.data.{ Kleisli, OptionT }
import cats.effect.Sync
import cats.effect.concurrent.Ref
import cats.syntax.all._
import io.circe.generic.auto._
import io.circe.syntax._
import org.http4s._
import org.http4s.circe.CirceEntityDecoder._
import org.http4s.circe._
#!/usr/bin/env bash
usage="Usage: $(basename "$0") region stack-name [aws-cli-opts]
where:
region - the AWS region
stack-name - the stack name
aws-cli-opts - extra options passed directly to create-stack/update-stack
"
@PurpleBooth
PurpleBooth / README-Template.md
Last active October 25, 2025 08:50
A template to make good README.md

Project Title

One Paragraph of project description goes here

Getting Started

These instructions will get you a copy of the project up and running on your local machine for development and testing purposes. See deployment for notes on how to deploy the project on a live system.

Prerequisites

@staltz
staltz / introrx.md
Last active October 22, 2025 12:20
The introduction to Reactive Programming you've been missing
@viktorklang
viktorklang / Future-retry.scala
Last active July 23, 2023 23:48
Asynchronous retry for Future in Scala
import scala.concurrent.duration._
import scala.concurrent.ExecutionContext
import scala.concurrent.Future
import akka.pattern.after
import akka.actor.Scheduler
/**
* Given an operation that produces a T, returns a Future containing the result of T, unless an exception is thrown,
* in which case the operation will be retried after _delay_ time, if there are more possible retries, which is configured through
* the _retries_ parameter. If the operation does not succeed and there is no retries left, the resulting Future will contain the last failure.