#memoization code explainers

ruby

require "csv"
 
class SalesReport
  def initialize(path)

Aggregating CSV sales data in Ruby

data-aggregation memoization group_by

Intermediate 6 steps

rust

use std::collections::HashMap;
 
pub struct Memoizer<K, V, F> {
    cache: HashMap<K, V>,

A generic memoizer in Rust

memoization generics caching

Intermediate 6 steps

java

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.math.BigInteger;

A thread-safe memoized factorial cache

memoization thread-safety caching

Intermediate 6 steps

python

from functools import wraps
 
 
def memoize(func):

Building a memoize decorator in Python

decorators closures memoization

Intermediate 5 steps

javascript

import { useMemo, useState } from 'react';
 
function ProductList({ products }) {
  const [query, setQuery] = useState('');

Memoizing a filtered list in React

memoization derived-state filtering

Intermediate 8 steps

ruby

module Fibonacci
  CACHE = Hash.new do |cache, n|
    cache[n] = cache[n - 1] + cache[n - 2]
  end

Memoizing Fibonacci with a Hash default block

memoization recursion hash-default

Intermediate 5 steps

ruby

class ProductCatalog
  def featured_products
    Rails.cache.fetch("catalog/featured_products", expires_in: 12.hours) do
      Product.where(featured: true)

Caching patterns with Rails.cache.fetch

caching cache-keys expiry

Intermediate 5 steps