Intermediate code explainers

ruby

require "set"
 
class FuzzySearch
  def initialize(candidates)

Building a ranked fuzzy search in Ruby

fuzzy-matching levenshtein ranking

Intermediate 9 steps

java

public final class ShippingAddress {
    private final String recipient;
    private final String line1;
    private final String line2;

Building immutable objects with the Builder pattern

builder-pattern immutability validation

Intermediate 7 steps

rust

use chrono::{DateTime, Duration, FixedOffset, Utc};
 
#[derive(Debug)]
pub struct EventWindow {

Parsing and measuring time windows in Rust

datetime error-handling pattern-matching

Intermediate 7 steps

php

final class UserActivityStream
{
    public function __construct(
        private readonly \PDO $db,

Streaming user activity with PHP generators

generators pagination lazy-evaluation

Intermediate 8 steps

typescript

import { DynamicModule, Module, Provider } from '@nestjs/common';
import Redis, { RedisOptions } from 'ioredis';
 
export const REDIS_CLIENT = Symbol('REDIS_CLIENT');

Building a dynamic Redis module in NestJS

dependency-injection dynamic-modules provider-tokens

Intermediate 8 steps

javascript

export function buildPaginationUrl(baseUrl, { page, perPage, filters = {}, sort } = {}) {
  const url = new URL(baseUrl);
  const params = url.searchParams;

Building and parsing pagination URLs

url-parsing query-string pagination

Intermediate 8 steps

go

package feed
 
import (
	"encoding/json"

Streaming a JSON array in Go

streaming json decoder

Intermediate 6 steps

java

import java.time.Instant;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;

Converting timestamps across time zones in Java

date-time time-zones instant

Intermediate 6 steps

rust

use axum::{
    extract::Path,
    http::{header::ACCEPT, HeaderMap, StatusCode},
    response::{Html, IntoResponse, Json, Response},

Content negotiation in an Axum handler

content-negotiation http-headers serialization

Intermediate 8 steps

php

<?php
 
namespace App\Casts;

How a custom Eloquent cast wraps an Address in Laravel

value-objects serialization data-mapping

Intermediate 7 steps

typescript

type Operator = "=" | "!=" | ">" | "<" | ">=" | "<=" | "LIKE";
 
type Row = Record<string, unknown>;

A type-safe SQL query builder in TypeScript

builder pattern generics method chaining

Intermediate 8 steps

javascript

import { useSearchParams } from "react-router-dom";
 
const TABS = [
  { id: "overview", label: "Overview" },

URL-driven tabs with React Router

url-state query-params accessibility

Intermediate 8 steps

rust

use axum::{extract::Multipart, http::StatusCode, Json};
use serde::Serialize;
use tokio::io::AsyncWriteExt;
use uuid::Uuid;

Streaming multipart uploads in Axum

multipart streaming async-io

Intermediate 10 steps

python

import re
from email_validator import validate_email, EmailNotValidError
 
_DISPOSABLE_DOMAINS = {

Normalizing signup emails in Python

validation normalization data-cleaning

Intermediate 8 steps

python

import time
from concurrent.futures import ThreadPoolExecutor, as_completed
from pathlib import Path

Parallel file downloads with a thread pool

concurrency thread-pool streaming-io

Intermediate 8 steps

rust

use std::collections::HashMap;
 
#[derive(Debug, Clone)]
struct Record {

Batched aggregation with fold in Rust

iterators fold hashmap

Intermediate 9 steps

typescript

import { Directive, ElementRef, HostListener, Input, OnDestroy, OnInit } from '@angular/core';
 
@Directive({
  selector: '[appTrapFocus]',

Building a focus-trap directive in Angular

accessibility focus-management dom

Intermediate 9 steps

java

package com.example.payments.config;
 
import com.stripe.StripeClient;
import org.springframework.beans.factory.annotation.Value;

Swapping payment gateways by profile in Spring

dependency-injection profiles configuration

Intermediate 6 steps