kata-tennis

This repo contains an implementation of Mark Seemann's KataTennis in Elm.

Mark wrote an article series called Types + Properties = Software.

The stronger a language's type system is, the more you can use static types to model your application's problem domain. With a sufficiently strong type system, you can make illegal states unrepresentable. While states are guaranteed to be legal, transitions between states need not be. You can often use Property-Based Testing to ensure that the state transitions are correct. The combination of types and properties give you a simple, but surprisingly powerful way of specifying the behaviour of the software you create.

Each article from the series has its own commit:

• ec3c836 – Designing with types
• 8bb7123 – State transition properties
• 6e5b06f – Properties for the advantage state
• 90fd83d – Properties for the Forties
• 3b06ca9 & 3f61ad0 & 4b0fd64 – Composition
• 0ae1df3 – Initial state & Finite state machine
• 22394a2 – Other properties

Running tests

To run tests, install node-test-runner, go to the root of the repo and call elm test from the terminal.