Understanding the differences between Iteraion, Recursion and Tail Recursion using a Scala example.

IterationRecursionTailRecursion.scala

object RecursionVsTailRecursion extends App {
  
	def iterative_sum(a: Long, b: Long):Long =  {
	  var result = 0L;
	  for(i <- a until b){result=result+i}
	  return result+b;
	}
  
  	def sum(a: Long, b: Long): Long = if(a > b) 0 else a + sum(a+1, b)
  	
  	def tail_sum(a: Long, b: Long): Long ={
  	  def loop(a: Long, acc: Long): Long = {
  	    if(a > b) acc
  	    else loop(a+1, acc+a)
  	  }
  	  loop(a, 0)
  	} 
  	  
  			
  	val last = 6998
  	println(iterative_sum(1, last))
  	println(tail_sum(1, last))
  	println(sum(1,last))

}