How to do memoization or memoisation in Julia 1.0

Question

I have been trying to do memorisation in Julia for the Fibonacci function. This is what I came up with.

The original unmodified code (for control purposes)

Answer 1

Since the arguments to the function are integers, you can use a simple array, which will be faster than a Dict (make sure you use BigInts in the cache for large arguments to avoid overflow):

function fib(n, cache=sizehint!(BigInt[0,1],n))
    n < length(cache) && return cache[n+1]
    f = fib(n-1,cache) + fib(n-2,cache)
    push!(cache,f)
    return f
end