So what is a loop ?
loops allow us to execute a statement or a block of statements multiple times. Like conditional statements, they are controlled by boolean expressions.

The for comprehension
Scala’s for is much more powerful than Java’s for Consequently, it is used much more often than the other kinds of loops.

Syntax − for loop

for( var x <- Range|List|Array... ){
   statement(s);
}

Example − for loop

// For Loops in Scala
object Demo {
  def main(args: Array[String]) {
    // for Loop with Ranges
    for (i <- 1.to(5)) {
      println("i using to " + i);
    }

    for (i <- 1 until 6) {
      println("i using until " + i);
    }

    // for Loop with multiple Ranges
    for (i <- 1 to 9; j <- 1 to 3) {
      println("i using multiple ranges " + i + " " + j);
    }

    // for Loop with Collections

    val lst = List(1, 2, 3, 5, 4, 6, 78, 9, 6, 5);

    for (i <- lst) {
      println("i using list " + i);
    }

    // for Loop with Filters
    for (i <- lst; if i < 6) {
      println("i using Filters " + i);
    }

    // for Loop as Expressions
    val result = for {
      i <- lst
      if i < 6
    } yield {
      i * i
    }

    println("result = " + result);

  }
}


/*
i using to 1
i using to 2
i using to 3
i using to 4
i using to 5
i using until 1
i using until 2
i using until 3
i using until 4
i using until 5
i using multiple ranges 1 1
i using multiple ranges 1 2
i using multiple ranges 1 3
i using multiple ranges 2 1
i using multiple ranges 2 2
i using multiple ranges 2 3
i using multiple ranges 3 1
i using multiple ranges 3 2
i using multiple ranges 3 3
i using multiple ranges 4 1
i using multiple ranges 4 2
i using multiple ranges 4 3
i using multiple ranges 5 1
i using multiple ranges 5 2
i using multiple ranges 5 3
i using multiple ranges 6 1
i using multiple ranges 6 2
i using multiple ranges 6 3
i using multiple ranges 7 1
i using multiple ranges 7 2
i using multiple ranges 7 3
i using multiple ranges 8 1
i using multiple ranges 8 2
i using multiple ranges 8 3
i using multiple ranges 9 1
i using multiple ranges 9 2
i using multiple ranges 9 3
i using lst 1
i using lst 2
i using lst 3
i using lst 5
i using lst 4
i using lst 6
i using lst 78
i using lst 9
i using lst 6
i using lst 5
i using Filters 1
i using Filters 2
i using Filters 3
i using Filters 5
i using Filters 4
i using Filters 5
result = List(1, 4, 9, 25, 16, 25)

*/