aakashns · August 29, 2015 14:17
diff --git a/sum.scala b/sum.scala
 // xs.foldLeft(z)(op) reduces to 
 // (..(((z op x(0)) op x(1)) op x(2)) ... op x(n)) 
 def sum(elems : Seq[Int]): Int =
  elems.foldLeft(0) { _ + _ }
diff --git a/sumDifference.scala b/sumDifference.scala
 def sumDifference(elems1: Seq[Int], elems2: Seq[Int]): Int =
  sum(elems1) - sum(elems2)
diff --git a/sumNonEmpty.scala b/sumNonEmpty.scala
 def sumNonEmpty(elems: Seq[Int]): Int =
  if (elems.isEmpty) None 
  else Some(sum(elems))
	def sumDifference(elems1: Seq[Int], elems2: Seq[Int]): Int =
	sum(elems1) - sum(elems2)
	def sumNonEmpty(elems: Seq[Int]): Int =
	if (elems.isEmpty) None
	else Some(sum(elems))