Learning Functional Programming in Go

Fibonacci sequence - a simple recursion and two performance improvements

The Fibonacci sequence is a sequence of numbers where each number is equal to the previous two numbers added together. Here's an example of this:

 1  1  2  3  5  8  13  21  34

So, 1 plus 1 is 2, 2 plus 3 is 5, 5 plus 8 is 13, and so on.

Let's use the Fibonacci sequence to help illustrate a number of concepts.

A recursive function is a function that calls itself in order to break down complex input into simpler ones. With each recursive call, the input problem must be simplified in such a way that eventually the base case must be reached.

The Fibonacci sequence can be easily implemented as a recursive function:

func Fibonacci(x int) int {    if x == 0 {        return 0    } else if x <=  ...