Katas

Table of Contents generated with DocToc

• Organizations and Official Challenges
• Kata Catalogues
• Individual Katas and Puzzles
• Kata Constraints: Harden the Exercises

Organizations and Official Challenges

• codewars - Train your skills by solving katas.
• CodeCrafters.io and CodeCrafters.io/Catalog - Challenges for experts.
• Cyber Dojo - a platform to host and facilitate coding dojos for solo, group and classroom adventures.
  • Cyber Dojo start-points - on GitHub.
• HackerRank
• CodinGame - Challenges in the shape of game programming.
• Code Golf - solve problems in the least number of characters
• Python Challenge - a game in which each level can be solved by a bit of (Python) programming.
• Rosetta Code - Solutions to programming problems in many different languages.
• The International Obfuscated C Code Contest

Kata Catalogues

• (Pragmatic) Dave Thomas: CodeKata - Introduction to “Kata” and a list of Katas.
• Anghel Leonhard: Java Coding Problems - a book containing many katas by topic
• Pietro Di Bello: A curated list of programming kata - Curated list, categorized and with difficulty rating.
• L. Falco, Learn With Llew, - Curated list with categories
• pinage404: Exercises / Katas - A list of kata catalogs
• Katalyst - many small programming problems known as Katas.
• Emily Bache: github://emilybache - many katas, front page lists refactoring katas.
• Steve Smith (aka ardalis): Coding Kata Catalog
• Coding Dojo: Kata Catalogue
• CCD School: Coding Dojo - various katas of different categories.
• CodeKata.com
• Gabe Montalvo: Awesome Katas
• Advent of Code - Advent calendar of small programming puzzles.
  • The New Stack: ‘Advent of Code’ Builds a Programming Community Around Puzzles
  • Difficulty Chart Day by Day 2018 - 2023 - associated reddit post
  • 2024 Day 25: Code Chronicle & Puzzle Difficulty Ranking
• Project Euler - a series of challenging mathematical/computer programming problems.
• Peter Kofler (Code Cop) - Code Cop’s repositories have some katas.
  • GitHub: Unit Testing Koans - Testing Koans to learn new programming languages.

Individual Katas and Puzzles

Refactoring

• David Denton: Refactoring Golf
• Christian Clausen: five-lines - A difficult refactoring kata addressed in the book “5 Lines of Code”.
• Emily Bache: Gilded Rose
• Emily Bache: Supermarket Receipt Refactoring Kata
• Gregor Riegler: Expense Report
• Roland Germ: DataValidator Refactoring Kata
• Johann Martinsson: Lift pass pricing - Hexagonal architecture refactoring kata.
• Peter Kofler: Bank OCR Refactoring - Primitive Obsession -> Erzeuge Klassen

Algorithms

• Codewars: Page replacement algorithms: clock (6 kyu)

Software Design

• Kata01: Supermarket Pricing - Software design kata (not necessarily code).
  • Chris F Carroll: Code Kata One as Code – Supermarket Pricing - Kata01 with instructions for coding.
  • Samman Technical Coaching Society: Supermarket Receipt - Different variations of Kata01.

Miscellaneous

• Codingame: How to draw the Mandelbrot set
• Rosettacode: Generate and Draw a Julia Set
• GitHub: SpecFlowOSS/SpecFlow-Examples - BowlingKata

This collection of katas helps you learn some Design Patterns [1, 2]:

• Adapter - Codewars: Geese to Ducks
• Bridge - Logging System
• Builder - WebShop
• Chain of Responsibility - Pokerhands
• Command - Mars Rover
• Decorator - Bicycle Inventory
• EventAggregator - IRC

Katas addressing other things than programming

• Eficode Academy - Exercises and best practices for everyone!
  • Git Katas - a collection of Git exercise.
  • Docker Katas - This workshop will take you from “Hello Docker” to deploying a containerized web application to a server.

Kata Constraints: Harden the Exercises

Object Calisthenics

• Jeff Bay: Object Calisthenics - PDF presentation.
• Jeff Bay: Object Calisthenics - Conference Paper (PDF).
• William Durand: Object Calistenics - Blog Post.

Functional Calisthenics

• Ian Johnson: Introducing functional calisthenics - Write up after SoCraTes UK 2015.
• Jorge Gueorguiev Garcia: Functional Calisthenics

TDD Flavour

To add TDD Flavour, do one or more of …

• Pair programming and TDD
  • Baby steps: Switch roles after 3(!) minutes; revert on red test after 3 min, i.e. hand over only green test state
• TDD as if you meant it (= Rules of Simple Design + TDD above, especially: minimal code)
• Handover on red test