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Scala @ PP

1. Installation

2. Syntax

2.1. Writing functions 2.2. Function evaluation (order of parameters in function call matters !)

  1. using the ⇒ to delay evaluation

2.3. Conditionals

  1. def f(x : Int) = if (x >= 0) x else -x
  2. boolean expressions (true, false, !b, &&, ||)
  3. the “by value” definition using val
  4. example using def and val against a loop

Newton square root estimation

* Blocks - expressions in Scala * visibility of variables in blocks * local scoping (similar to let) * semicolons (optional) * tail recursion in Scala (only direct recursive calls are optimised @tailrec) * function types (f : Int ⇒ Int) * anonymous functions ((x: Int, y: Int) ⇒ x + y, x ⇒ x+x) * currying (def f(x: Int, y: Int)(z: Int):Int = x+y+z) * higher-order functions (mapReduce implementation)

* classes and methods 

class Rational(x: Int, y: Int) { // creates a Type as well as a constructor for the new type
    def a = x
    def b = y
}
 
val r = new Rational(1,2)
  • toString and @override