noelmarkham

package nm

import cats._
import cats.implicits._

import cats.data.WriterT

object Mocking {

noelmarkham

import...	What it imports
cats.std.type	Typeclass instances for standard library type (think List, Option)
cats.syntax.type	“Enhanced” methods for type (.toRightXor etc)
cats.data.type	Imports a type not part of the standard library (think Xor, Kleisli) and its typeclass instances

noelmarkham

Keybase proof

I hereby claim:

• I am noelmarkham on github.
• I am noel (https://keybase.io/noel) on keybase.
• I have a public key whose fingerprint is 89A2 B6E9 B309 3F3A 752B 705A 2660 0E7B 872A 52AB

To claim this, I am signing this object:

noelmarkham

import shapeless._
import shapeless.ops.hlist.IsHCons

object ShapelessDojo {

  def addOneToCaseClass[C, H <: HList, E, T <: HList]
      (c: C)
      (implicit gen: Generic.Aux[C, H],
                h:   IsHCons.Aux[H, E, T],
                ev:  E =:= Int,

noelmarkham

scala> import org.scalacheck._
import org.scalacheck._

scala> val generatedFunc = Gen.resultOf[String => Int, String => Int](identity).sample.get
generatedFunc: String => Int = <function1>

scala> generatedFunc("hello") == generatedFunc("goodbye")
res0: Boolean = true

noelmarkham

  // Given a case class where the first two elements have the same type, swap those values:
  def swap[T, U <: HList, H1, H2, T1 <: HList, T2 <: HList](v: T)(
    implicit // proofs:

      // Case class T can be represented by U
      // (U is an output, must be used as an output before using it as an input in the proofs below)
      gen: Generic.Aux[T, U],

      // U is composed of H1 :: T1
      isc1: IsHCons.Aux[U, H1, T1],

noelmarkham

scala> :paste
// Entering paste mode (ctrl-D to finish)

import org.scalacheck.Prop.forAll
import org.scalacheck.Properties
import shapeless.contrib.scalacheck._

case class WebServerConfig(hostname: String, port: Int)
case class ApplicationConfig(webServer: WebServerConfig)

noelmarkham

object FlakyFunctionTest {

  import scalaz._
  import Scalaz._

  var state = false

  val function: Unit => String = scalaz.Memo.immutableHashMapMemo { _ =>
    println(s"We received a call")

noelmarkham

scala> usernameToUserIdLens.get("Alan").foreach(println)
** SELECT ID FROM USERS WHERE NAME = Alan
1

scala> userIdToStreetNameLens.get(1).foreach(println)
** SELECT STREET_NAME FROM ADDRESS WHERE USER_ID = 1
High Street

scala> val usernameToStreetNameLens = usernameToUserIdLens >=> userIdToStreetNameLens

noelmarkham

scala> val FL = Functor[List]
FL: scalaz.Functor[List] = scalaz.std.ListInstances$$anon$1@575f20e3

scala> val FF = Functor[Future]
FF: scalaz.Functor[scala.concurrent.Future] = scalaz.std.FutureInstance@678bc1a9

scala> val FF_FL = FF compose FL
FF_FL: scalaz.Functor[[α]scala.concurrent.Future[List[α]]] = scalaz.Functor$$anon$1@49487384

scala> val values = Future(List(1, 2, 3, 4, 5))