gistfile1.scala

// Nth Item
 
import scala.annotation.tailrec
 
def find(list: List[Int], item: Int) : Int = {
  @tailrec def f(l: List[Int], i: Int, acc: Int): Int =
    if(l.head == i) acc
 
    else f(l.tail, i, acc+1)
 
  f(list, item, 0)
}
 
 
val index = find(List(1, 2, 3, 4, 5, 6, 7, 8, 9), 9)
 
s"The item is at position ${index}"
 
// Higher-Order Functions
def values = (f: Int => Int, x: Int, y: Int) => for (i <- x to y) yield (i, f(i))
 
values(x => x*x, -2, 2)
 
// Composing Predicates
def isEven = (x: Int) => if (x % 2 == 0) true else false
 
val negate = (f: Int => Boolean) => (x: Int) => !f(x)
 
val isOdd = negate(isEven)
 
isEven(2)
isOdd(3)