Scala Reading Notes ch3-ch4

• First Steps in Scala

1. One of the main characteristics of a functional language is that functions are first class construct, and that's very true in Scala.
2. Iterate with foreach and for : args.foreach(arg => println(arg)).
3. In this code, you call the foreach method on args, and pass in a function.
4. args.foreach((arg : String) => println(arg))
5. args.foreach(println)
6. for (arg <- arg="" args="" li="" println="">

• Next Steps in Scala

1. val greetStrings = new Array[String](3)
2. greetStrings(0) = "Hello" ...
3. for (i <- 0="" 2="" greetstrings="" i="" li="" print="" to="">
4. val greetStrings : Array[String] = new Array[String](3)
5. greetString(0) = "Hello" will be transformed into greetStrings.update(0, "Hello")
6. val numNames = Array("zero", "one", "two")
7. val oneTwo = List(1, 2); val threeFour = List(3, 4); val oneTwoThreeFour = oneTwo ::: ThreeFour;
8. val pair = (99, "Luftballons"); println(pair._1); println(pair._2)
9. var jetSet = Set("Boeing", "Airbus"); jetSet += "Lear"; jetSet.contains"Cessna"; 
10. val hashSet = HashSet("Tomatoes", "Chilies")
11. val treasureMap = Map[Int, String](); treasureMap += (1 -> "Go to island.");

• Something

1. (x: Int, y:Int) => x + y : 这是一个匿名函数的定义，可以把它赋值给一个不变量；
2. def add(x: Int, y: Int): Int = {x + y} : 这是一个正常函数的定义；
3. Remeber : Concise is Nice !
4. thrill.mkString(", ") equals ",".join(thrill) in python