Fib in Groovy

int fib(int num) {
  if(num < 2)
    return num
    return fib(num-1) + fib(num-2)
}

// Com tail-call
def fibTail(int num, BigInteger i = 1, BigInteger k = 0) {
  if(num <= 0)
    return k
  return fibTail(num-1, i+k, i)
}

// Com otimizacao de tail-call (sem StackOverflowError)
def fibTailOpt
fibTailOpt = {int num, BigInteger i = 1, BigInteger k = 0 ->
    if(num <= 0)
        return k
    return fibTailOpt.trampoline(num-1, i+k, i)
}.trampoline()

def test(func, arg) {
    t1 = System.nanoTime()
    res = func(arg)
    t2 = System.nanoTime()
    println "Tempo: ${(t2-t1)/1000000000}"
    println "Resultado: ${res}"
}

n = args[0].toInteger()
test(fibTailOpt, n)
test(this.&fibTail, n)
test(this.&fib, n)