scala functions

extractor.scala

class CC[T] { def unapply(a:Any):Option[T] = Some(a.asInstanceOf[T]) }

object M extends CC[Map[String, Any]]
object L extends CC[List[Any]]
object S extends CC[String]
object D extends CC[Double]
object B extends CC[Boolean]

for {
    Some(M(map)) <- List(JSON.parseFull(jsonString))
     //这里的<- 和 = 会调用unapply
    L(languages) = map("languages")
    M(language) <- languages
    S(name) = language("name")
    B(active) = language("is_active")
    D(completeness) = language("completeness")
} yield {
    (name, active, completeness)
}


//another example

"jack" match { case S(x)=>println(x)}

function.scala

//curried 2.9.x
def say(a:Int,b:Int)  = a+b //函数

val fun = say(2,_:Int) //函数值Int=>Int<function1>

val cud =  (say(_:Int,_:Int)).curried
cud(2)(3)

val say2 = Function.uncurried(cud)
say2(2,3)

scala evaluator interpret.scala

import scala.tools.nsc.{Interpreter,Settings}
var i = new Interpreter(new Settings(str => println(str)))
i.interpret("class Test { def hello = \"Hello World\"}")

scala> var res = Array[AnyRef](null)
scala> i.bind("result", "Array[AnyRef]", res)
scala> i.interpret("result(0) = new Test")
scala> res
res11: Array[AnyRef] = Array(Test@2a871dcc)

var res = Array[(Int,Int)=>Int](null)
i.bind("result", "Array[(Int,Int)=>Int]", res)
i.interpret("result(0) ={def say(a:Int,b:Int) = a+b; say _}")

scalaz-io-monad.scala

//我给你一个花生，至于有没有花生米，你自己打开看下就知道了。Option/Maybe
import scalaz._
import scalaz._
import scalaz.effects._
import java.io._
 
object TheIO extends App {
 
  val dirInIO = io { new File(System.getProperty("user.dir")) }
 
  def filesInIO = for (dir <- dirInIO) yield dir.listFiles()
 
  def namesInIO = for (theFiles ← filesInIO) yield theFiles.map(_.getName())
 
  def printNamesInIO = for (all ← namesInIO) yield all.map(println(_))
 
  val result = printNamesInIO
 
  println("Nothings happened yet, lets go!")
  result.unsafePerformIO
}