Exercise 2.2 of Functional Programming In Scala

gistfile1.scala

FILE "isSorted.scala"

def isSorted[A](as: Array[A], ordered: (A,A) => Boolean): Boolean = {
  @annotation.tailrec
  def go(n: Int): Boolean =
    if (n >= as.length-1) true
    else if (!ordered(as(n), as(n+1))) false
    else go(n+1)
  go(0)
}


def customOrder(n:Int, m:Int)= n <= m



SCALA REPL
scala> :load isSorted.scala
Loading isSorted.scala...
isSorted: [A](as: Array[A], ordered: (A, A) => Boolean)Boolean
customOrder: (n: Int, m: Int)Boolean

scala> isSorted(Array(1,1,2,3,2), customOrder)
res0: Boolean = false

scala> isSorted(Array(1,1,2,2,3), customOrder)
res1: Boolean = true

scala> isSorted(Array(3,2), customOrder)
res2: Boolean = false

scala> isSorted(Array(1,2), customOrder)
res3: Boolean = true

scala> isSorted(Range(1,20).toArray, customOrder)
res4: Boolean = true