1 // Scala is about expressions

     2 //

     3 //

     4 

     5 1 + 2

     6 

     7 val r1 = 1 + 2

     8 val r2 = r1 * r1

     9 

    10 val new_list = 

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

    12 

    13 

    14 def my_not_equal(x: Int, y: Int) : Boolean = {

    15  !(x == y)

    16 }

    17 

    18 

    19 // why return is not needed in Scala

    20 

    21 def sum_even(ls: List[Int]): Int = {

    22   val aux = for (x <- ls) yield {

    23     if (x % 2 == 0) x else 0

    24   }

    25   aux.sum

    26 }

    27 

    28 sum_even(List(1,2,3,4,5,6))

    29 

    30 def sum_return(ls: List[Int]): Int = {

    31   val aux = for (x <- ls) yield {

    32     if (x % 2 == 0) (return x) else (return 0)

    33   }

    34   aux.sum[Int]

    35 }

    36 

    37 sum_return(List(2,3,4,5,6))

    38 

    39 

    40 // replace subexpressions should not 

    41 // change the meaning, but with return it does:

    42 

    43 def sq1(n: Int): Int = n * n

    44 def sq2(n: Int): Int = return n * n

    45 

    46 def sum_squares(ls: List[Int]): Int = {  

    47   (for (n <- ls) yield (return n * n)).sum[Int]

    48 }

    49 

    50 sum_squares(List(1,2,3,4,5,6))