Introduction to Scalaz

Author: egimaben

build.sbt

@@ -90,14 +90,17 @@ lazy val scala_akka = (project in file("scala-akka"))
   )
 
 val monocleVersion = "2.0.4"
+val scalazVersion = "7.3.2"
 lazy val scala_libraries = (project in file("scala-libraries"))
     .settings(
       name := "scala-libraries",
       libraryDependencies += "org.scalatest" %% "scalatest" % "3.0.5" % Test,
       libraryDependencies ++= Seq(
         "com.github.julien-truffaut" %% "monocle-core" % monocleVersion,
         "com.github.julien-truffaut" %% "monocle-macro" % monocleVersion,
-        "com.github.julien-truffaut" %% "monocle-law" % monocleVersion % "test"
+        "com.github.julien-truffaut" %% "monocle-law" % monocleVersion % "test",
+        "org.scalaz" %% "scalaz-core" % scalazVersion,
+        "junit" % "junit" % "4.13" % Test
       )
    )
 

scala-libraries/src/main/scala/com/baeldung/scala/scalaz/ScalazExamples.scala

@@ -0,0 +1,69 @@
+package com.baeldung.scala.scalaz
+
+import scalaz._
+
+object ScalazExamples {
+  case class UserId(id: Long)
+  case class FullName(fname: String, lname: String)
+  case class User(id: UserId, name: FullName)
+  val userFullName = Lens.lensu[User, FullName](
+    (user, name) => user.copy(name = name),
+    _.name
+  )
+  val firstName = Lens.lensu[FullName, String](
+    (fullName, firstName) => fullName.copy(fname = firstName),
+    _.fname
+  )
+
+  val lastName = Lens.lensu[FullName, String](
+    (fullName, lastName) => fullName.copy(lname = lastName),
+    _.lname
+  )
+  val userFirstName = userFullName >=> firstName
+  val userLastName = userFullName >=> lastName
+
+  implicit object threadShow extends Show[Thread] {
+    override def show(f: Thread): Cord =
+      Cord(s"Thread id = ${f.getId}, name = ${f.getName}")
+  }
+
+  case class Score(amt: Double)
+  implicit object scoreOrdered extends Order[Score] {
+    override def order(x: Score, y: Score): Ordering =
+      x.amt compare y.amt match {
+        case 1  => Ordering.GT
+        case 0  => Ordering.EQ
+        case -1 => Ordering.LT
+      }
+  }
+
+  //enum
+  case class Priority(num: Int, name: String)
+  val HIGH = Priority(3, "HIGH")
+  val MEDIUM = Priority(2, "MEDIUM")
+  val LOW = Priority(1, "LOW")
+
+  implicit object PriorityEnum extends Enum[Priority] {
+    def order(p1: Priority, p2: Priority): Ordering =
+      (p1.num compare p2.num) match {
+        case -1 => Ordering.LT
+        case 0  => Ordering.EQ
+        case 1  => Ordering.GT
+      }
+
+    def succ(s: Priority): Priority = s match {
+      case LOW    => MEDIUM
+      case MEDIUM => HIGH
+      case HIGH   => LOW
+    }
+
+    def pred(s: Priority): Priority = s match {
+      case LOW    => HIGH
+      case MEDIUM => LOW
+      case HIGH   => MEDIUM
+    }
+
+    override def max = Some(HIGH)
+    override def min = Some(LOW)
+  }
+}