AterraEngine.Unions 0.7.0-alpha

🔗 AterraEngine.Unions 🔗

A Union Library for DotNet

Overview

AterraEngine.Unions is a comprehensive library for creating and managing union types in .NET. It leverages the latest features of C# 13.0 and .NET 9.0 to provide a robust and efficient framework for representing multiple and diverse data types as a single unit. The package was inspired by the OneOf package.

Features

• Type Safety: Ensure type safety with union types that encapsulate various data forms.
• Ease of Use: Simplified API to integrate union types seamlessly into your project.
• Performance Optimizations: Designed with performance in mind to handle high-scale applications.
• Generate: Not satisfied with the basic unions we have made for you? No worries, you can generate your own using AterraEngine.Unions.Generator
• Auto Alias: Instead of having a pre-made Union<T0,T1,...> base type which simply provides a IsT0 or AsT1 api, this package generates all unions from the ground up.
  • This allows us to create insert any names we want. By default, it will choose the name of the types chosen for the aliases, example : IsTrue AsString.
  • You can also set your own alias for specific types using the attribute [UnionAliases(aliasT2:"Something")]. See usage in the example below.
• Up to 16: By default the IUnion<> interface allows up to 16 types within the union. Because we use casting instead of the index based approach by OneOf, there doesn't need to be a limit to this in the future.

Getting Started

Installation

You can install AterraEngine.Unions via NuGet Package Manager:

dotnet add package AterraEngine.Unions

You can install AterraEngine.Unions.Generator via NuGet Package Manager:

dotnet add package AterraEngine.Unions.Generator

Usage

Here is a basic example to demonstrate how to create and use union types with AterraEngine.Unions.

using AterraEngine.Unions;

TrueOrFalse trueOrFalse = new True();

if (trueOrFalse.IsTrue) {    
    // Do stuff here
}

using AterraEngine.Unions;

ManyOneNoneOrError<int, string> union = new Many<int>([1, 2, 3]);
if (union.TryGetAsMany(out Many<T> values) {
  // Do stuff here
}
if (union.TryGetAsOne(out One<T> value) {
  // Do stuff here
}
if (union.TryGetAsNone(out None value) {
  // Do stuff here
}
if (union.TryGetAsError(out Error<T> value) {
  // Do stuff here
}

Using .Value will incur boxing. If you want to avoid boxing, it is currently advised to use the TryGetAs{TypeName} method or a combination of Is{TypeName} and As{Typename} properties.

using AterraEngine.Unions;

ManyOneNoneOrError<int, string> union = new One<int>(1);
switch (union.Value) {
    case Many<int>: //...
    case One<int>: //...
    case None: //...
    case Error: //...
}

if (union.TryGetAsNone(out None value) {
    // ...        
}

Another version of using the switch case would be like the following example. Although a little more cumbersome to write, it will do the same as the above example, without boxing.

TrueOrFalse union = new False();
switch (union) {
    case {IsTrue: true, AsTrue: var trueValue}: 
        Assert.Equal(new True(), trueValue);
        break;
    case {IsFalse: true, AsFalse: var falseValue}: 
        Assert.Equal(new False(), falseValue);
        break;
}

You can directly use the predefined Union<> and Union<T0, T1, ...> structs provided by AterraEngine.Unions for common use cases. This struct has the downside of it's aliases being named isT0, asT0, etc and is this less easy to follow along what is being referenced.

using AterraEngine.Unions;

public class UnionExample {
    public Union<string, int> GetSomeValue(bool input) {
        if (input) return "Something";
        else return 0;
    }
}

Creating your own unions is easily done by installing AterraEngine.Unions.Generators and following the example:

using AterraEngine.Unions;

[UnionAliases(aliasT2:"ErrorTuple")]
public readonly partial struct TrueFalseOrErrorTuple() : IUnion<True, False, (Error<string>, Type)>;
// Which will generate the following, instead of a default generated name for the 3rd type in the union.
// - IsErrorTuple
// - AsErrorTuple
// - TryGetErrorTuple(...)

Here is an advanced example demonstrating a custom union type with user-defined aliases:

using AterraEngine.Unions;

[UnionAliases(aliasT2: "ErrorTuple")]
public readonly partial struct TrueFalseOrErrorTuple : IUnion<True, False, (Error<string>, Type)>;

class Program {
    static void Main() {
        TrueFalseOrErrorTuple union = new True();
        
        if (union.IsTrue) {
            Console.WriteLine("It's true!");
        }

        // Using the custom alias
        union = new ((new Error<string>("An error occurred"), typeof(int)));

        if (union.IsErrorTuple) {
            var errorTuple = union.AsErrorTuple;
            Console.WriteLine($"Error: {errorTuple.Item1.Message}, Type: {errorTuple.Item2}");
        }
    }
}

Benchmarks

The following is a result of the benchmarks found at Benchmarks.AterraEngine.Unions.

Normal benchmarks:

Enhanced benchmarks