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F# scripting for a component based game engine

21 Apr 2014

Recently Andrew added C# scripting capabilities to Duality, the engine we are using to build Honourbound. Once we had something working, we started thinking about the fact that it might be pretty simple to add support for [F#][fsh], so we did.

A few weekends ago I twitted this:

tweet

We had a spike working within a few hours with an old version of F# codedom. I spent some time the last few days making it more usable within the editor.

How to use

If you are like me, you'll want to try this out as soon as possible, instructions :D

Steps to move a gameObject with an F# script if you never used Duality

module Dualityscript

open ScriptingPlugin
open Duality
open Duality.Components
open Duality.Helpers
open OpenTK

type FSharpScript() =
    inherit DualityScript()

    override this.Update()=        
        this.GameObj.Transform.Pos <- this.GameObj.Transform.Pos + new Vector3(1.0f,0.0f,0.0f)

If you want to build all yourself :

A video showing this here.

Why

Game programming in a middle to big sized project falls into three logical categories. Those categories are associated with their level of use: i.e: how often you run this code, and the rate of change i.e. how many times this file has changed in the last month.

Engine: Core game engine, doesn't change too often, ideally it has lots of test coverage.

Game Systems: These are game specific systems that are core to the game, the change more often than the engine. This code has a high re usability level so should be tested.

Gameplay: The code here changes all the time, the general pattern is a lot of initial churn and then some tweaks. We agreed not to test this code, tho there are some exceptions.

I think using F# with a functional approach in our GamePlay code will make us more efficient because of the frequency of change this type of code requires. It might help reduce the number of NullReferenceException type of errors too.

Thanks

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