danclien

object DietCakePattern {
  /***** Dependency *****/
  trait EngineComponent {
    val engine: Engine
    class Engine {
      def start: Unit = println("engine.start: vroom")
    }
  }
  
  /***** Dependent implementation *****/

danclien

/***** Dependency *****/
trait EngineComponent {
  val engine: Engine
  // class Engine {
  //   def start: Unit = println("engine.start: vroom")
  // }
}


/***** Dependent implementation *****/

danclien

function bind(/* (M a) */ monadicValue, /* (a -> M b) */ operation ) {
  //Step 1: Unwrap `monadicValue` so type `(M a)` so it's of type `a`
  //Step 2: Shoves the `a` through the `operation`
    //How it shoves a through the operation depends on what you want it to do
  //Step 3: Returns a monadic value of type `(M b)`
}


/* Maybe/Option monad 
 * If the value is None/Nothing, stop and return None/Nothing,

danclien

function Some(value) {
  this.value = value;
}

Some.prototype.bind = function(f) {
  return f(this.value);
}

function None() { 
}

danclien

function Some(value) {
  this.value = value;
}

Some.prototype.flatMap = function(f) {
  return f(this.value);
}

Some.prototype.map = function(f) {
  return new Some(f(this.value));

danclien

• Use GitHub's default .gitignore file for Scala
  • Add .DS_Store/ to .gitignore
• Use ./project/Build.scala over ./Build.sbt
• Add to ./project/plugins.scala with latest version numbers

addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.10.1")

addSbtPlugin("com.timushev.sbt" % "sbt-updates" % "0.1.2")

danclien

/* Routing trait for mixing in routes */
trait RoutingService extends Directives { this: HttpServiceActor =>
  private val EmptyRoute: Route = { context => Unit }
  def routes: Route = EmptyRoute

  /* Used to concatenate `Route`s together */
  def concatRoutes(superRoutes: Route)(routes: Route): Route = superRoutes match {
    case EmptyRoute => routes
    case _ => superRoutes ~ routes
  }

danclien

// Enter :paste mode

trait Length[M[_]] {
  def length[A](xs: M[A]): Int
}

object Length {
  implicit val LengthList: Length[List] = new Length[List] {
    def length[A](xs: List[A]): Int = {
      xs.length

danclien

Usability Lab Notes

Notes from @shalinpei and @llewrek.

Notes

• 2 rooms, one lab and one observation
• Observation room
  • One-way mirror
  • Tables

danclien

List(1,2,3,4,5).foldRight(List.empty[Int])(_ :: _)
//res1: List[Int] = List(1, 2, 3, 4, 5)


/*
  Passing in the type constructors for an abstract data type to its fold method
  is the identity function.

  List is made up of `Nil` and `Cons` objects.
*/