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jdegoes /
Last active Dec 29, 2019
Possible ZIO Workshops
  • Scheduling & Retrying with ZIO: A 2 hour workshop that shows how to create and use schedules and retry policies with ZIO. Scheduling covers cache use cases, downloading resources, sending emails; retrying covers flaky web APIs, database connections, etc.
  • ZIO CRUD. A 2 hour workshop showing how to build a basic REST API using ZIO + third-party library.
  • Using ZIO with Legacy Code: A 2 hour workshop that shows how to wrap lots of legacy code: sync code, async code, Future code; and demonstrate use of Runtime to unsafeRun at boundary points for roundtrip integration.
  • Crash Course in ZIO: A 2 hour workshop that covers “hello world” and a few other simple examples of writing programs with ZIO, with an emphasis on thinking functionality (values & operators on values) and using ‘for’ comprehensions successfully.
  • Rethinking Error Management: A 2 hour workshop that shows how to effectively use recoverable and non-recoverable errors, as well as lossless errors, to build resilient apps that
View gadts-session1.scala
package net.degoes.zio
trait Sql {
type ColumnName
type TableName
sealed trait Table[+A]
* (SELECT *, "foo", table.a + table.b AS sum... FROM table WHERE cond) UNION (SELECT ... FROM table)
View mini-zio.scala
final case class ZIO[-R, +E, +A](run: R => Either[E, A]) {
final def map[B](f: A => B): ZIO[R, E, B] =
ZIO(r => run(r).map(f))
final def flatMap[R1 <: R, E1 >: E, B](f: A => ZIO[R1, E1, B]): ZIO[R1, E1, B] =
ZIO(r => run(r).flatMap(a => f(a).run(r)))
final def provide(r: R): ZIO[Any, E, A] =
ZIO(_ => run(r))
jdegoes / zio-sky.scala
Last active Nov 27, 2019
ZIO Workshop - Sky
View zio-sky.scala
package net.degoes.zio
import zio._
import scala.annotation.tailrec
import scala.concurrent.ExecutionContext
trait Helpers {
implicit class ZIOExtensions[R, E, A](zio: ZIO[R, E, A]) {
val exited: ZIO[R, Nothing, Int] = zio.fold(_ => 1, _ => 0)
jdegoes / zio-test.scala
Last active Feb 6, 2020
Simple example of testing with ZIO environment
View zio-test.scala
object test {
import scalaz.zio._
type UserID = String
case class UserProfile(name: String)
// The database module:
trait Database {
val database: Database.Service
View Hangman.scala
// Create a type class to describe `printLine` and `readLine`.
trait Console[F[_]] {
def printLine(line: String): F[Unit]
def readLine: F[String]
jdegoes / fpmax.scala
Created Jul 13, 2018
FP to the Max — Code Examples
View fpmax.scala
package fpmax
import scala.util.Try
object App0 {
def main: Unit = {
println("What is your name?")
val name = readLine()
jdegoes / afp-examples.scala
Last active Feb 12, 2019
Example code from Applied Functional Programming with Scala
View afp-examples.scala
package lambdaconf.introfp2
// import scalaz._
// import Scalaz._
object functions {
object totality {
///def f[A]: A = null
def g[A]: A = throw new Error
View GameWorld.scala
object game {
case class Lens[S, A](set: A => S => S, get: S => A) { self =>
def >>> [B](that: Lens[A, B]): Lens[S, B] =
Lens[S, B](
set = (b: B) => (s: S) => self.set(that.set(b)(self.get(s)))(s),
get = (s: S) => that.get(self.get(s))
case class Prism[S, A](set: A => S, get: S => Option[A]) { self =>
jdegoes / AsyncToIO.scala
Last active Nov 11, 2017
A sketch of an `Async ~> IO`
View AsyncToIO.scala
val AsyncToIO: NaturalTransformation[Async, IO] {
def apply[A](fa: Async[A]): IO[A] = {
for {
ref <- newIORef[Either[Throwable, A]](Left(new Error("No value")))
counter <- IO(new java.util.concurrent.CountDownLatch(1))
_ <- fa.register(v => ref.set(v).flatMap(_ => IO(counter.countDown()))
_ <- IO(counter.await())
v <- ref.get
a <- v match {
case Left(e) =>
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