tailcall_examples.js

function sum(numbers, i = 0) {
  if (i === numbers.length) {
    return 0
  }
  return numbers[i] + sum(numbers, i+1)
}
console.log(sum([1,2,3,4,5]))


function sumTail(numbers, i = 0, sum = 0) {
  if (i === numbers.length) {
    return sum
  }
  return sumTail(numbers, i+1, sum + numbers[i])
}

console.log(sumTail([1,2,3,4,5]))


function factorial(n) {
  if (n === 1) {
    return 1
  }
  return n * factorial(n-1)
}

console.log(factorial(10))

function factorialTail(n, fact = 1) {
  if (n === 1) {
    return fact
  }
  return factorialTail(n-1, fact * n)
}

console.log(factorial(10))

function fibonacci(n, memo = []) {
  if (n < 2) {
    return n
  }
  if (!memo[n]) {
    memo[n] = fibonacci(n - 1, memo) + fibonacci(n - 2, memo)
  }
  return memo[n]
}

console.log(fibonacci(100))

function fibonacciTail(n, current = 0, next = 1) {
  if (n === 0) {
    return current
  }
  return fibonacciTail(n-1, next, current + next)
}

console.log(fibonacciTail(100))