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