NESCALA NOTESby Hung Lin @hunglin

nescala 20132 days event in PhiladelphiaDay 1: 17 talksSpeakers from typesafe, twitter, tumblr, ...Scala book authors: , Day 2: $50 entrance fee

Bill Venners Josh Suerethunconference

Function Patterns for theAsynchronous Web

by Josh Suereth @ TypeSafe, author of Scala in Depth

The new WebAsynchronousEvent drivenData drivenBig dataSingle page designComposition of servicesUser experiences

Futurefuture { // Do sometime later ...} map { result => // Do something with result ...}

Monadic Flowdef render(data: DbResult): Future[Html] = future(Html(...))def handleRequest(...): Unit = { for { data <- query(...) html <- render(data) } yield writeHtml(socket, html)}

Joinval users: Future[DbResult] = query(...)val projects: Future[DbResult] = query(...)val data: Future[(DbResult, DbResult)] = (users zip projects)

List[Future[DbResult]] -> Future[List[DbResult]]

The Essence of the Iterator PatternJeremy Gibbons and Bruno C. d. S. Oliveira @ Oxford University Computing Laboratory

Monadic MapApplicative FunctorsMonadic Applicative Functors...

Cake Patternby Daniel Spiewak, Code Commit

Not only for DependencyInjection

trait UserRepositoryComponent { val userRepository: UserRepository

class UserRepository { ... }}

trait UserServiceComponent { this: UserRepositoryComponent =>

val userService: UserService

class UserService { ... }}

Traits are modulestrait UserModule { def loadUser(id: Long): User}trait TweetModule { def post(userId: Long, body: String)}trait MySQLUserModule extends UserModule { ... }trait TwitterModule extends TweetModule with UserModule { ... }val universe = new MySQLUserModule with TwitterModule {}

Package is just a namespace to avoid name collision. So,instead import, use extends/with

Explicit dependencies

Interesting problem #1

solution: use def or lazy val

trait A { val foo: String}trait B extends A { val bar = foo + "World"}class C extends B { val foo = "Hello" println(bar)}

Interesting problem #2

solution: use val

trait A { object stuff { object Foo object Bar object Baz} }trait B extends A { object moar { object Foo object Baz object Bar} }

abstract override trait TraitA { def method1(l: List[String]): List[String] } trait TraitB extends TraitA { override def method1(l: List[String]) = l :+ "traitB" }

trait TraitC extends TraitA { abstract override def method1(l: List[String]) = super.method1(l) :+ "traitC" } class ClassA { this: TraitA => def show() { println(method1(List("ClassA"))) } }

Advanced Stream Processing

Programming + Math

Finagle

scala.collection.approximate

Play! 2 Framework

Dependency management

Day 2: UnconferencetypeclassunapplyScalaTestand a lot more

8 people attendedgave 5 talks

precog

Audax @ nescala 2014more people attendgive talks (Lift, ScalaTest, ...)projects @ unconference