Counting Booleans

betterCounting

def isEven(x:Int) = (x % 2 == 0)
def isPositive(x: Int) = (x > 0)
def aList = List(1,2,-2,34,57, -91, -90)
// in this case I go from [Int] => [Bool] => Int. 2 times, because I have 2 functions.
val (numEven, numPos) = (aList.map(isEven).filter(_ == true).length, aList.map(isPositive).filter(_ == true).length)            

originalCounting

def isEven(x:Int) = (x % 2 == 0)
def isPositive(x: Int) = (x > 0)
def aList = List(1,2,-2,34,57, -91, -90)
// in this case I go from [Int] => (Int,Int)
val (numEven, numPos) = aList.foldLeft((0,0)) { case ((howManyEven, howManyPos), n) => 
                            (howManyEven + (if (isEven(n)) 1 else 0), howManyPos + (if (isPositive(n)) 1 else 0))
                        }
            

+1