Minimalist Scalaz Hello World App

This assumes you are using OSX, have Java 8 or greater installed and have brew installed.

$ brew install sbt

Hello World

Using https://github.com/scala/scala-seed.g8 create a Hello World application.

$ sbt new scala/scala-seed.g8 --name=scalaz-scratch
$ cd scalaz-scratch
$ sbt run 
  [info] Running example.Hello
  hello
  [success]

Adding in scalaz

As per https://github.com/scalaz/scalaz add to build.sbt:

libraryDependencies += scalaTest % Test,
libraryDependencies += "org.scalaz" %% "scalaz-core" % "7.2.23",
libraryDependencies += "org.scalaz" %% "scalaz-effect" % "7.2.23"

Using scalaz in the HelloWorld App

Replace src/main/example/Hello.scala with:

    package example

    import scalaz.effect.IO
    import scalaz.effect.IO.putStrLn

    object Hello extends Greeting with App {
    
      def greeting: String = "hello"
    
      val printHello: IO[Unit] = putStrLn(greeting)
    
      printHello.unsafePerformIO
    }
    
    trait Greeting {
      def greeting: String
    }

Running the scalaz version

$ sbt run
  [info] Running example.Hello
  hello
  [success]

$ sbt console
scala> example.Hello.main(Array())

Running the tests

$ sbt test

Where to go next