Naive Implementation of Automatic Memoisation

Question

I wrote code to (naively) perform automatic memoisation. I tried to write it in a functional programming style, and so did not make use of any global variables.

My Code

def naive_memoise(caches):
    def memoise(f):
        nonlocal caches
        def mem_f(n):
            nonlocal caches, f
            if f not in caches:
                caches[f] = {}
            if n not in caches[f]:
                caches[f][n] = f(n)
            return caches[f][n]
        return mem_f
    return memoise

Sample Usage

def fib(n):
    if n in [0, 1]:
        return n
    return  fib(n - 2) + fib(n - 1)

mem = naive_memoise({})
fib = mem(fib)

Answer 1

This looks good to me and I have nothing important to add.

• the nonlocal are not required here

• in the code sample, you could use the @decorator syntax

• maybe you could write something more generic than just functions taking a single parameter.