Scala for rubyists
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This document discusses Scala and compares it to other languages like Ruby and Java. It covers Scala's features like functional programming, object-oriented programming, pattern matching, implicit parameters, monads, actors and testing frameworks. Pros and cons are listed for Scala and other languages like Clojure and Erlang. The document encourages learning Scala through online courses and exercises.
var labels = Set[String](“”)
Y los tipos?
Colecciones Inmutables
Syntaxis para generics <?>
NO HAY ; :D
Que es val ?](https://image.slidesharecdn.com/scalaforrubyists-150702131539-lva1-app6891/85/Scala-for-rubyists-12-320.jpg)
![Scala OOP
14
Case class -> get, set, constructor auto
Traits son similares a los modulos
en Ruby
Generic clases/traits
Singleton Object
case class SocialNetwork(id: String, name: String)
trait LinkedList[+A] {
def isEmpty: Boolean
def head: A
def tail: LinkedList[A]
def at(index: Int): A
def prepend[B >: A](elem: B): LinkedList[B] =
new Cons(elem, this)
}
object Nil extends LinkedList[Nothing] {
class Cons[A](val head: A, val tail: LinkedList[A]) extends LinkedList[A] {](https://image.slidesharecdn.com/scalaforrubyists-150702131539-lva1-app6891/85/Scala-for-rubyists-14-320.jpg)
![Monads
18
map, flatMap, filter
for comprehension
def readAsync(): Future[Option[List[String]]] =
Future { readFile() }
def readFile(): Option[List[String]] =
Try { Source.fromURL("/tmp/file.txt").getLines().toList
} toOption
val futSize: Future[Int] =
for {
result <- readAsync()
list <- result
} yield list.size
val futSizeMap: Future[Option[Int]] =
readAsync().map { result: Option[List[String]] =>
result.map((list: List[String]) => list.size)
}
Future, Option, Try, Either](https://image.slidesharecdn.com/scalaforrubyists-150702131539-lva1-app6891/85/Scala-for-rubyists-18-320.jpg)
![ScalaTest
20
Test Unit
trait NeoTest
extends FunSpec
with MustMatchers
with BeforeAndAfterAll
with BeforeAndAfterEach {
override def beforeEach(): Unit = {
NeoDBCleaner.cleanDB()
}
describe("UserDAOs") {
it("creates an user an checks the default group") {
withUser { (user, saved) =>
saved must be(true)
val query = s"""match (a:user {id: "${user.id.getOrElse("")}"})-[c:has_group]->(b:group) return a, b, c"""
val result = Await.result(NeoQuery.executeQuery[UserLogin, Group, HasGroupLogin](query), 2 seconds)
result.length must be(1)
}
}
}
}
Multiples Pardigmas
TDD
BDD](https://image.slidesharecdn.com/scalaforrubyists-150702131539-lva1-app6891/85/Scala-for-rubyists-20-320.jpg)
Scala for rubyists
- 1. Scala for Rubyists Make your ideas come true by Michel Perez www.mrkaspa.com
- 2. Ruby :D FELICIDAD TIPADO DINAMICO GEMS NO IDE DOCUMENTACION FACIL DE APRENDER
- 3. Ruby :( PERFORMANCE ESCALABILIDAD PROG FUNCIONAL MANTENIBILIDAD CONCURRENCIA
- 5. I <3 Java - JVM - Libraries - Performance - Escalabilidad - Mantenibilidad SCALA CLOJURE JRUBYGROOVY
- 6. 6
- 7. 7 PROS CONS Primitivas de concurrencia Desarrollado por Google Tiempo de compilación Lenguaje compilado Lenguaje tipado Sintaxis old style Demasiado imperativo Poco funcional Inmutabilidad
- 8. 8 PROS CONS Primitivas de concurrencia Erlang Lenguaje interpretado Funcional Muy nuevo
- 9. 9 PROS CONS Primitivas de concurrencia Funcional JVM Lenguaje interpretado Sistema de tipado opcional LISP
- 10. 10 PROS CONS Akka Funcional JVM Tipado Compilado Tiempo de compilación Curva de aprendizaje Gestión de dependencias
- 11. Programacion funcional FUNCIONES Y MAS FUNCIONES INMUTABILIDAD CURRYING CLOSURES LAZY EVALUATION PATTERN MATCHING CAMBIA LA MANERA EN COMO PROGRAMAS
- 12. Scala Variables? 12 val labels = Set(“") val labels = Set[String](“”) var labels = Set[String](“”) Y los tipos? Colecciones Inmutables Syntaxis para generics <?> NO HAY ; :D Que es val ?
- 13. Scala OOP + FP 13 No es la OOP el demonio? Un buen programador de scala no usa side efect Funciones puras Usa OOP para abstraer datos class Rational(x: Int, y: Int) { def this(x: Int) = this(x, 1) private def gcd(a: Int, b: Int): Int = if (b == 0) a else gcd(b, a % b) private val g = gcd(x, y) def numer = x / g def denom = y / g def < (o: Rational) = numer * o.denom < o.numer * denom def > (o: Rational) = !(this < o) def +(o: Rational) = { new Rational(numer * o.denom + denom * o.numer, denom * o.denom) } def -(o: Rational) = { this + (-o) } def unary_- = Rational(-numer, denom) override def toString = { numer + "/" + denom } } Cada cambio de estado genera un nuevo objeto
- 14. Scala OOP 14 Case class -> get, set, constructor auto Traits son similares a los modulos en Ruby Generic clases/traits Singleton Object case class SocialNetwork(id: String, name: String) trait LinkedList[+A] { def isEmpty: Boolean def head: A def tail: LinkedList[A] def at(index: Int): A def prepend[B >: A](elem: B): LinkedList[B] = new Cons(elem, this) } object Nil extends LinkedList[Nothing] { class Cons[A](val head: A, val tail: LinkedList[A]) extends LinkedList[A] {
- 15. Scala Functions 15 Toda funciona debe tener un tipo de retorno(type inference) Funciones como parámetros Retorna funciones Vector.fill(queens.length)("* “) .updated(col, "X ").mkString def lambda = (x: Int) => x + 1 val multiplier = (i:Int) => i * 10 def sumComp(a: Int): (Int) => Int = { def sum(b: Int) = a + b } val fun = sumComp(5) fun(1) def sumComp(a: Int)(b: Int): Int = { a + b } Currying
- 16. Pattern Matching 16 Es un Super Switchval secondElement = List(1,2,3) match { case x :: y :: xs => y case _ => 0 } val foodItem = "porridge" def goldilocks(expr: Any) = expr match { case (`foodItem`, _) => "eating" case ("chair", "Mama") => "sitting" case ("bed", "Baby") => "sleeping" case _ => "what?" } goldilocks(("porridge", "Papa")) Compara y extrae al mismo tiempo
- 17. Implicits 17 Parametros inyectados en un metodo o constructor de manera implicita Sirve para realizar conversiones automaticas implicit def implChange(str:String):Int = new Integer(str) def sum(a:Int, b:Int):Int = a +b sum("1", 2)
- 18. Monads 18 map, flatMap, filter for comprehension def readAsync(): Future[Option[List[String]]] = Future { readFile() } def readFile(): Option[List[String]] = Try { Source.fromURL("/tmp/file.txt").getLines().toList } toOption val futSize: Future[Int] = for { result <- readAsync() list <- result } yield list.size val futSizeMap: Future[Option[Int]] = readAsync().map { result: Option[List[String]] => result.map((list: List[String]) => list.size) } Future, Option, Try, Either
- 19. Actors 19 Hilos livianos Orientados a eventos class BloodRequester extends Actor { implicit val executor = context.dispatcher override def receive: Receive = { case BloodRequest(request) => DonorDAO.findNear(request).map { donors => donors.foreach { donor => facebookNotifier ! FacebookNotify(donor, request) } } } } Se reinician en caso de fallas Supervisión
- 20. ScalaTest 20 Test Unit trait NeoTest extends FunSpec with MustMatchers with BeforeAndAfterAll with BeforeAndAfterEach { override def beforeEach(): Unit = { NeoDBCleaner.cleanDB() } describe("UserDAOs") { it("creates an user an checks the default group") { withUser { (user, saved) => saved must be(true) val query = s"""match (a:user {id: "${user.id.getOrElse("")}"})-[c:has_group]->(b:group) return a, b, c""" val result = Await.result(NeoQuery.executeQuery[UserLogin, Group, HasGroupLogin](query), 2 seconds) result.length must be(1) } } } } Multiples Pardigmas TDD BDD
- 21. Scala wants U ;) 21 https://www.coursera.org/course/progfun http://scala-exercises.47deg.com/koans