Introduction

Helm is a functionally reactive game engine written in Haskell and built around the Elerea FRP framework. Helm is heavily inspired by the Elm programming language (especially the API). All rendering is done through a vector-graphics based API. At its core, Helm is built on SDL and the Cairo vector graphics library, but is designed with the ability to interface with other graphical engine back-ends.

In Helm, every piece of input that can be gathered from a user (or the operating system) is hidden behind a signal. For those unfamiliar with FRP, signals are essentially a value that changes over time. These signals can then be combined with other signals, producing new signals that map the old data into new data. This sort of architecture, when used for a game, allows for pretty simple, clean (and in my opinion, artistic) code.

This guide is still heavily a work-in-progress. The aim of the guide is to give you tips and tutorials that are not easily gathered from the documentation, which can be daunting at first.

Background Reading

• The Elm Architecture
• Eventless Reactivity from Scratch
• Arrowized FRP