Scala @ PP

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