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Use kind-projector plugin #1

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6 changes: 3 additions & 3 deletions build.sbt
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,8 @@ scalaVersion := "2.10.4"

resolvers ++= Seq(
"snapshots" at "http://oss.sonatype.org/content/repositories/snapshots",
"releases" at "http://oss.sonatype.org/content/repositories/releases"
"releases" at "http://oss.sonatype.org/content/repositories/releases",
"bintray/non" at "http://dl.bintray.com/non/maven"
)

libraryDependencies ++= Seq(
Expand All @@ -21,7 +22,6 @@ libraryDependencies ++= Seq(
"org.specs2" %% "specs2" % "1.13" % "test"
)



addCompilerPlugin("org.spire-math" %% "kind-projector" % "0.5.2")


2 changes: 1 addition & 1 deletion src/main/scala/eg/FreeMonad.scala
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Expand Up @@ -20,7 +20,7 @@ object FreeMonad extends App {

// The instance is not inferrable
implicit val monadTerminalIO: Monad[TerminalIO] =
Free.freeMonad[({type λ[α] = Coyoneda[TerminalOp, α]})#λ]
Free.freeMonad[Coyoneda[TerminalOp, ?]]

// Smart constructors
def readLine: TerminalIO[String] = Free.liftFC(ReadLine)
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6 changes: 3 additions & 3 deletions src/main/scala/eg/ST.scala
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Expand Up @@ -14,14 +14,14 @@ object ST extends App {

// In order to run an action, you need to construct a Forall, which is awkward.
// Note that it fixes the return type.
val forall = new Forall[({ type λ[σ] = ST[σ, Int] })#λ] { def apply[S] = a }
val forall = new Forall[ST[?, Int]] { def apply[S] = a }

// We can abstract out the lambda type if we want to
type ForallST[A] = Forall[({ type λ[σ] = ST[σ, A] })#λ]
type ForallST[A] = Forall[ST[?, A]]
val forall2 = new ForallST[Int] { def apply[S] = a }

// They should be equivalent (N.B. might crash presentation compiler but does work)
implicitly[Forall[({ type λ[σ] = ST[σ, Int] })#λ] =:= ForallST[Int]]
implicitly[Forall[ST[?, Int]] =:= ForallST[Int]]

// this is pure
val x0 = runST(forall)
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6 changes: 3 additions & 3 deletions src/main/scala/eg/StateT.scala
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Expand Up @@ -13,11 +13,11 @@ import scalaz.effect.MonadIO

object StateTExample extends App {

// // To avoid the type lambda ({type λ[a] = StateT[IO,String,a]})#λ
// // To avoid the type lambda StateT[IO,String,?]
// // in the call to liftIO below, we will just make an alias.
// type StringIO[+A] = StateT[IO, String, A]
//
// // The tricky part is the lifting.
// // The tricky part is the lifting.
// val action: StringIO[Int] =
// for {
// s <- get[String].lift[IO]
Expand All @@ -38,7 +38,7 @@ object StateTExample2 extends App {

type M[A] = EitherT[IO, Error, A]

type Op[A] = StateT[({ type λ[+α] = EitherT[IO, Error, α] })#λ, Running, A]
type Op[A] = StateT[EitherT[IO, Error, +?], Running, A]

implicit def liftio = new MonadIO[Op] {
def point[A](a: => A): Op[A] = unit(a)
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