Switch from Scalaz to Cats

CHANGELOG.md

@@ -84,3 +84,9 @@ change.
 * Update Shapeless to 2.3.3
 * Update Scalaz to 7.2.18
 * Update Gerweck Utils to 2.7.2
+
+### 0.14
+
+* Migration from Scalaz to Cats
+  * This is the library we use to provide `Monad` and `Applicative` instances
+    for observable values.

build.sbt

@@ -19,7 +19,7 @@ lazy val root = (project in file ("."))
       gerweckUtil,
       scalaJava8,
       scalaFx,
-      scalaz,
+      cats,
       shapeless
     ),
 

project/Dependencies.scala

@@ -24,7 +24,7 @@ object Dependencies {
   final val scalaParserVersion = "1.0.4"
   final val scalaXmlVersion    = "1.0.5"
   final val gerweckUtilVersion = "2.7.2"
-  final val scalazVersion      = "7.2.18"
+  final val catsVersion        = "1.0.1"
   final val shapelessVersion   = "2.3.3"
   final val scallopVersion     = "1.0.1"
 
@@ -39,7 +39,7 @@ object Dependencies {
   val gerweckUtil     = "org.gerweck.scala"      %% "gerweck-utils"      % gerweckUtilVersion
   val gerweckUtilAkka = "org.gerweck.scala"      %% "gerweck-utils-akka" % gerweckUtilVersion
   val scalaJava8      = "org.scala-lang.modules" %% "scala-java8-compat" % scalaJava8Version
-  val scalaz          = "org.scalaz"             %% "scalaz-core"        % scalazVersion
+  val cats            = "org.typelevel"          %% "cats-core"          % catsVersion
   val shapeless       = "com.chuusai"            %% "shapeless"          % shapelessVersion
   val scallop         = "org.rogach"             %% "scallop"            % scallopVersion
 

project/ProjectSettings.scala

@@ -15,6 +15,7 @@ trait ProjectSettings
   override final val extraScalaVersions    = Seq("2.11.11")
   override final val defaultOptimize       = true
   override final val defaultOptimizeGlobal = false
+  override final val extraScalacOptions    = Seq("-Ypartial-unification")
 
   override final val sonatypeResolver      = true
 

src/main/scala/org/gerweck/scalafx/util/observable.scala

@@ -2,7 +2,7 @@ package org.gerweck.scalafx.util
 
 import language.implicitConversions
 
-import scalaz._
+import cats._
 
 import scalafx.beans.property._
 import scalafx.beans.value._
@@ -16,7 +16,7 @@ trait ObservableImplicits {
    * a property in a tight loop, I expect you'll have bigger performance
    * issues.)
    */
-  implicit val observableInstances = new Applicative[Observable] with Functor[Observable] with Monad[Observable] {
+  implicit object observableInstances extends Applicative[Observable] with Functor[Observable] with Monad[Observable] {
     /* Map can be derived from `ap`, but this adds less overhead. */
     override def map[A, B](a: Observable[A])(f: A => B): ReadOnlyObjectProperty[B] = {
       @inline def recalculate(): B = f(a.value)
@@ -38,12 +38,12 @@ trait ObservableImplicits {
       prop
     }
 
-    def point[A](a: => A): ReadOnlyObjectProperty[A] = {
+    override def pure[A](a: A): ReadOnlyObjectProperty[A] = {
       ObjectProperty[A](a)
     }
 
     /* Ap can be derived from `point` and `bind`, but this has less overhead. */
-    override def ap[A, B](fa: => Observable[A])(f: => Observable[A => B]): ReadOnlyObjectProperty[B] = {
+    override def ap[A, B](f: Observable[A => B])(fa: Observable[A]): ReadOnlyObjectProperty[B] = {
       @inline def recalculate(): B = (f.value)(fa.value)
 
       val originalValue = recalculate()
@@ -66,13 +66,18 @@ trait ObservableImplicits {
       prop
     }
 
-    /* Aka `flatMap` */
+    override def flatMap[A, B](fa: Observable[A])(f: A => Observable[B]): ReadOnlyObjectProperty[B] = {
-    override def bind[A, B](fa: Observable[A])(f: A => Observable[B]): ReadOnlyObjectProperty[B] = {
+      flatten(map(fa)(f))
-      join(map(fa)(f))
     }
 
-    /* Aka `flatten` */
+    override def tailRecM[A, B](a: A)(f: A => Observable[Either[A, B]]): Observable[B] = {
-    override def join[A](ooa: Observable[Observable[A]]): ReadOnlyObjectProperty[A] = {
+      this.flatMap(f(a)) {
+        case Right(b)    => pure(b)
+        case Left(nextA) => tailRecM(nextA)(f)
+      }
+    }
+
+    override def flatten[A](ooa: Observable[Observable[A]]): ReadOnlyObjectProperty[A] = {
       @inline def oa() = ooa.value
       @inline def calc(): A = oa().value
 
@@ -109,12 +114,18 @@ trait ObservableImplicits {
     }
   }
 
-  implicit val readOnlyObjectPropertyInstances = new Applicative[ReadOnlyObjectProperty] with Functor[ReadOnlyObjectProperty] with Monad[ReadOnlyObjectProperty] {
+  implicit object readOnlyObjectPropertyInstances extends Applicative[ReadOnlyObjectProperty] with Functor[ReadOnlyObjectProperty] with Monad[ReadOnlyObjectProperty] {
     override def map[A, B](a: ReadOnlyObjectProperty[A])(f: A => B): ReadOnlyObjectProperty[B] = observableInstances.map(a)(f)
-    override def point[A](a: => A): ReadOnlyObjectProperty[A] = observableInstances.point(a)
+    override def pure[A](a: A): ReadOnlyObjectProperty[A] = observableInstances.pure(a)
-    override def ap[A, B](fa: => ReadOnlyObjectProperty[A])(f: => ReadOnlyObjectProperty[A => B]): ReadOnlyObjectProperty[B] = observableInstances.ap(fa)(f)
+    override def ap[A, B](f: ReadOnlyObjectProperty[A => B])(fa: ReadOnlyObjectProperty[A]): ReadOnlyObjectProperty[B] = observableInstances.ap(f)(fa)
-    override def bind[A, B](fa: ReadOnlyObjectProperty[A])(f: A => ReadOnlyObjectProperty[B]): ReadOnlyObjectProperty[B] = observableInstances.bind(fa)(f)
+    override def flatMap[A, B](fa: ReadOnlyObjectProperty[A])(f: A => ReadOnlyObjectProperty[B]): ReadOnlyObjectProperty[B] = observableInstances.flatMap(fa)(f)
-    override def join[A](ooa: ReadOnlyObjectProperty[ReadOnlyObjectProperty[A]]): ReadOnlyObjectProperty[A] = {
+    override def tailRecM[A, B](a: A)(f: A => ReadOnlyObjectProperty[Either[A, B]]): ReadOnlyObjectProperty[B] = {
+      flatMap(f(a)) {
+        case Right(b)    => pure(b)
+        case Left(nextA) => tailRecM(nextA)(f)
+      }
+    }
+    override def flatten[A](ooa: ReadOnlyObjectProperty[ReadOnlyObjectProperty[A]]): ReadOnlyObjectProperty[A] = {
       /* NOTE: this is copy-pasted from `observableInstances`. TBD: Find a way to share this. */
       @inline def oa() = ooa.value
       @inline def calc(): A = oa().value
@@ -197,11 +208,11 @@ final class RichObservable[A, C](val self: ObservableValue[A, C]) extends AnyVal
   @inline private def oapp = observableInstances
 
   def map[B](f: A => B) = oapp.map(self)(f)
-  def flatMap[B](f: A => Observable[B]) = oapp.bind(self)(f)
+  def flatMap[B](f: A => Observable[B]) = oapp.flatMap(self)(f)
-  def <*>[B](f: Observable[A => B]): ObservableValue[B, B] = oapp.ap(self)(f)
+  def <*>[B](f: Observable[A => B]): ObservableValue[B, B] = oapp.ap(f)(self)
   def tuple[B](f: Observable[B]): Observable[(A,B)] = oapp.tuple2(self, f)
-  final def *>[B](fb: ObjObs[B]): Observable[B] = oapp.apply2(self,fb)((_,b) => b)
+  final def *>[B](fb: ObjObs[B]): Observable[B] = oapp.map2(self,fb)((_,b) => b)
-  final def <*[B](fb: ObjObs[B]): Observable[A] = oapp.apply2(self,fb)((a,_) => a)
+  final def <*[B](fb: ObjObs[B]): Observable[A] = oapp.map2(self,fb)((a,_) => a)
 
   final def |@|[B, B1](fb: ObservableValue[B, B1]) = ObservableTupler(self, fb)
 

src/main/scala/org/gerweck/scalafx/util/package.scala

@@ -8,8 +8,6 @@ import scalafx.scene.input._
 import scalafx.scene.layout.GridPane
 import scalafx.scene.text.Text
 
-import scalaz._
-
 /** Various implicits and global utilities for ScalaFX work.
   *
   * @author Sarah Gerweck <sarah@atscale.com>