Macro cached

macro_rules! cached {
    (fn $name:ident ($($arg:ident: $arg_type:ty), *) -> $ret:ty = $body:expr) => { ... };
}

Macro for defining functions whose result needs to be cached.

Example

use once_cell::sync::Lazy;
use std::sync::Mutex;
use memory_cache::{MemoryCache, cached};

cached! {
    fn factorial(x: u128) -> u128 = {
        if x <= 1 {
            1
        } else {
            x * factorial(x - 1)
        }
    }
}

assert_eq!(factorial(21), 51090942171709440000);