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scala examples
// prime number generator
for (i <- 2 to 1000)
if((2 to i).find( j=> (i % j == 0 && i != j) ) == None)
println(i)
// function currying example
def matcher(haystack: List[Char])(needle: String) = {
haystack contains needle.charAt(0)
}
def isInitialUpperCase = matcher(List('A','B','C','D','E','F','G','H','I','L','M','N','O','P','Q','R','S','T','U','V','Z')) _
isInitialUpperCase("Fe")
val upperCased = {
if (isInitialUpperCase("fe")) "fe"
else "Fe"
}
List("Federico","federico","Andrea").filter(isInitialUpperCase)
// immutability
val x = 2
var mutableX = 3
x = 3; // no!
mutableX = 4; // yes
val m = Map("1" -> "one")
m("1") = "ONE"; // it does work, but it's not assigning, it's returning a new Map
import scala.collection.mutable.Map
val m = Map("1" -> "one") // this time does not use default immutable Map, but mutable Map
m("1") = "ONE"; // updates inline
// pattern matching examples
x match {
Case 2 => println(“two”)
Case a: Int => println(“an integer”)
Case _ => throw new Exception(“error”)
}
abstract class Fruit
case object Apple extends Fruit
case object Pear extends Fruit
def act(X: Fruit) = X match {
case Pear => "i like pears"
case Apple => "i do not like apples"
case _ => "fruit not recognized"
}
act(Pear) // java.lang.String = i like pears
act(Apple) // java.lang.String = i do not like apples
// trait example
trait Dad {
def getRole = " my role is Dad "
}
trait Lazyness {
def getTemperament = " i am a lazy person "
}
class Human(name: String) {
def getName = "my name is " + this.name
}
class Man(name: String) extends Human(name) with Dad
val man = new Man("Jon") with Lazyness
println(List(man.getName, man.getRole, man.getTemperament).reduceLeft(_ + ", " + _))
// trait example 2
abstract class Human2(name: String) {
def getName = "my name is " + this.name
}
trait Dad2 extends Human2 {
abstract override def getName = "i am a dad, and " + super.getName
}
class Man2(name: String) extends Human2(name) with Dad2
val man2 = new Man2("John smith")
println(man2.getName)
// various - bbc news reader
import java.net._
val url = new URL("http://feeds.bbci.co.uk/news/rss.xml")
val xmlPayload = XML.load(url)
(xmlPayload \\ "item").foreach( item => println( (item \ "title").text) )
// actor example
val a = actor {
loop {
receive {
case x: Int => println(x)
case _ => ()
}
}
}
a ! 2
a ! "no print"
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