C#, Functional Programming & Unity3D
Artūras Šlajus
arturas@tinylabproductions.com
What this talk is about
- Not deeply technical
- Functional programming is something that you need to wrap your head around
How did we get here
- Imperative OOP programmer from 2002 to 2012
- Discovered FP in 2012
- Been doing a mix of imperative + functional for games from 2015
Why does it matter
- More correct, robust software
- Reliance on compiler to point out errors for us
- Long update cycles
- Building 60 games - about 12 hours
- Publishing 60 games - about an hour
- Waiting for users to update - about a week
- Medium sized team
- Lots of change can mean lots of breakage
Core ideas
Honest Functions
public static int parseInt(string str);
public Player findPlayerIn(int x, int y);Honest Functions
public void updateState(
Vector3 movement,
bool animating, string animationType
);Honest Functions
public class Player : MonoBehaviour {
public void init(FooManager fooManager) {
...
}
}Honest Functions
public class Player : MonoBehaviour {
public class Init {
public Init(FooManager fooManager) {
...
}
}
}Things you are using but really should not
null
// Not honest
public Player findPlayer(int x, int y);
// Honest
public Option<Player> findPlayer(int x, int y);We haven't seen an NPE in ages.
Exceptions
// Not honest
public static int parseInt(string str);
// Somewhat honest
public static bool tryParseInt(
string str, out int parsed
);
// Honest
public static Either<string, int> parseInt(
string str
);Things that are really useful
Future/Task
Represents a value that may be available in the future.
TLPLib - Future, no threading support
C# stdlib - Task, with threading, heavy
Reactive Extensions (RX)
Represents a value stream.
Think of LINQ for events
TLPLib - integrated with library, no threading support
Unirx - standalone, more C#ish, threading support, heavier
Build validations
[SerializeField, NotNull]
GameObject bulletPrefab;
[SerializeField, NonEmpty]
List<GameObject> enemyPrefabs;Available in TLPLib
What do you need
C# 6 or 7
- Let me google that for you
- unity c# 6
- https://bitbucket.org/alexzzzz/unity-c-5.0-and-6.0-integration/src
- Using C# 6 for 1.5 years, no problems whatsoever
- Makes development so much more bearable.
TLPLib
- Optional. You can always use other libraries - roll out your own.
- https://github.com/tinylabproductions/tlplib
- Production ready.
FP in C# book
- Highly recommended
- Explains the ideas in more detail
- https://www.manning.com/books/functional-programming-in-c-sharp
Summary
- Please don't lie in your functions
- Applying FP results in more robust, correct and easier to understand code.
- Use the right tool for the job - neither imperative nor FP is the ultimate paradigm.
- If you take away 1 thing from this talk: let it be the banishment of nulls and usage of Option type.
- FP is a journey. You'll need to take a step back to go forwards.
Thank you
https://slides.com/arturasslajus/c-sharp-fp-unity3d
Artūras Šlajus
arturas@tinylabproductions.com
C#, FP & Unity3D
By Artūras Šlajus
