memoize-a-function-with-cached

Memoize a function with cached

The phrase "memoize a function" means "create a cache of the function's inputs and outputs". This is called memoizaiton, and can significantly speed up some functions, especially ones that do large calculations, or ones that do recursive calculations.

An easy way to memoize a function is to use the Rust cached crate.

Example:

use cached::proc_macro::cached;

#[cached]
fn fibonacci(n: usize) -> usize {
    if n == 0 || n == 1 { return n }
    fibonacci(n-1) + fibonacci(n-2)
}

The example defines a function named fibonacci. The Fibonacci sequence is a mathematical sequence in which each number is the sum of the two preceding ones: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, etc. For example, index number 0 is the sequence term 0, and index number 12 is the sequence term 144.

The fibonacci function takes an input which is a Fibonacci sequence index number, and returns the Fibonacci sequence term number. For example, input index 0 returns term 0, and input index 12 returns term 144.

By default, the function's memoizaiton cache will be the function's name in all caps i.e. FIBONACCI.