Qqwy / haskell-snek

A simple implementation of Snake. Runs in a terminal

Snek

This repo is an example implementation of the game of Snake, running in the terminal.

How to build/run

Install GHC and Stack by following the instructions of GHCUp

• Run stack run to first create an executable and then run it
• Run stack repl to load the modules into GHCi where you can interact with them

Design choices

This project is intended to be simple. As such, instead of using a full-fledged terminal-UI library (like vty or brick) it contains the code of what little it needs to do user-interaction at the terminal itself.

This means:

• Terminal drawing is done in a primitive fashion, which means that the game might sometimes 'flicker' a little, and when quitting you will see earlier states of the game when you scroll up.
• As Snake is a real-time game, reading user input has to happen in non-blocking fashion. However, reading from standard input is blocking. To circumvent the problem, we start a second thread which is allowed to block. Whenever a new keypress happens, this is communicated to the main thread using an MVar.

Another design choice (but a common one for Haskell projects), is to follow the 'imperative shell, pure core' idiom. This makes the different parts very easy to test and refactor.