fib

fibn.fs

let fibn n =
    let rec loop i a b =
        if i >= n then a
        else loop (i+1) b (a+b)
    loop 0 0 1

fibn.kt

fun fibn(n: Int): Int {
    tailrec fun loop(i: Int, a: Int, b: Int): Int {
        return if (i >= n) a
        else loop(i+1, b, a+b)
    }

    return loop(0, 0, 1)
}

fibn.re

let fibn = n => {
  let rec loop = (i, a, b) => {
    if (i >= n) a
    else loop(i+1, b, a+b)
  }
  loop(0, 0, 1)
}

fibn.scala

def fibn(n: Int): Int = {
  @scala.annotation.tailrec
  def loop(i: Int, a: Int, b: Int): Int = {
    if (i >= n) a
    else loop(i+1, b, a+b)
  }

  loop(0, 0, 1)
}