// Lecture 1

//===========

// Value assignments

// (variable names should be lower case)

//======================================

val x = 42

val y = 3 + 4

// Collections

//=============

List(1,2,3,1)

Set(1,2,3,1)

1 to 10

(1 to 10).toList

(1 until 10).toList

// an element in a list

List(1, 2, 3, 1)(0)

List(1, 2, 3, 1)(3)

1::2::3::Nil

List(1, 2, 3) ::: List(4, 5, 6)

// Printing/Strings

//==================

println("test")

val tst = "This is a " ++ "test\n" 

println(tst)

val lst = List(1,2,3,1)

println(lst.toString)

println(lst.mkString("\n"))

// some methods take more than one argument

println(lst.mkString("[", ",", "]"))

// Conversion methods

//====================

List(1,2,3,1).toString

List(1,2,3,1).toSet

"hello".toList

1.toDouble

List(1,2,3,4).reverse

// Types

//=======

/* Scala is a strongly typed language

 * Base types

    Int, Long, BigInt, Float, Double

    String, Char

    Boolean

 * Compound types 

    List[Int],

    Set[Double]

    Pairs: (Int, String)        

    List[(BigInt, String)]

*/

// Smart Strings

//===============

println(">\n<")

println(""">\n<""")

/* in Java

val lyrics = "Baa, Baa, Black Sheep \n" +

             "Have you any wool? \n" +

             "Yes, sir, yes sir \n" +

             "Three bags full"

*/ 

val lyrics = """Baa, Baa, Black Sheep  

                |Have you any wool?

                |Yes, sir, yes sir

                |Three bags full""".stripMargin

println(lyrics)

// Pairs/Tuples

//==============

val p = (1, "one")

p._1

p._2

val t = (4,1,2,3)

t._4

// Hello World

//=============

// show an example of a stand-alone scala file

// remind that in the course work you are asked a 

// plain scala "work-sheet"

// Function Definitions

//======================

def square(x: Int): Int = x * x

square(6)

// If control structure

//======================

def fact(n: Int): Int = 

  if (n == 0) 1 else n * fact(n - 1)

/* boolean operators

   ==     equals

   !      not

   && ||  and, or

*/

def fact2(n: BigInt): BigInt = 

  if (n == 0) 1 else n * fact2(n - 1)

fact2(150)

def fib(n: Int): Int =

  if (n == 0) 1 else

    if (n == 1) 1 else fib(n - 1) + fib(n - 2)

//gcd - Euclid's algorithm

def gcd(a: Int, b: Int): Int =

  if (b == 0) a else gcd(b, a % b)

gcd(48, 18)

// String Interpolations

//=======================

val n = 3

println("The square of " + n + " is " + square(n) + ".")

println(s"The square of ${n} is ${square(n)}.")

def gcd_db(a: Int, b: Int): Int = {

  println(s"Function called with ${a} and ${b}.")

  if (b == 0) a else gcd_db(b, a % b)

}

gcd_db(48, 18)

// Assert/Testing

//================

// For-Comprehensions (not For-Loops)

//====================================

for (n <- (1 to 10).toList) yield square(n)

for (n <- (1 to 10).toList; 

     m <- (1 to 10).toList) yield m * n

val mult_table = 

  for (n <- (1 to 10).toList; 

       m <- (1 to 10).toList) yield m * n

mult_table.sliding(10,10).mkString("\n")

// with patterns

for ((m, n) <- List((1, 4), (2, 3), (3, 2), (4, 1))) yield m + n 

for (p <- List((1, 4), (2, 3), (3, 2), (4, 1))) yield p._1 + p._2 

// Webpages

//==========