Dusharp 0.2.0

Dusharp

Dusharp is a C# source generator for creating discriminated unions. This library allows you to define union types with ease, using attributes and partial methods. It is inspired by functional languages but built for C# developers.

Features

• ✅ Create unions: Define discriminated unions using attributes.
• ✅ Match method: Pattern match on union cases in a type-safe way.
• ✅ Equality: Automatic equality comparison for unions.
• ❌ Pretty print: Using overloaded ToString() (coming soon).
• ❌ JSON serialization/deserialization: Support for unions with System.Text.Json (coming soon).
• ❌ Struct unions: With efficient memory layout for unions as structs (coming soon).

Installation

Dusharp is available as a NuGet package. You can install it using the NuGet package manager:

dotnet add package Dusharp

Usage

Dusharp uses attributes to generate discriminated unions and case methods. Here's how to get started:

1. Define a Union

To define a union, annotate a class with the [Dusharp.UnionAttribute] attribute.

using Dusharp;

[Union]
public partial class Shape { }

2. Define Union Cases

Define union cases by creating public static partial methods and marking them with the [Dusharp.UnionCaseAttribute] attribute. The method body will be automatically generated.

using Dusharp;

[Union]
public partial class Shape
{
    [UnionCase]
    public static partial Shape Circle(double radius);

    [UnionCase]
    public static partial Shape Rectangle(double width, double height);
}

3. Match on Union

You can easily perform pattern matching on a union using the Match method. The source generator will create the Match method based on the defined union cases.

Shape shape = Shape.Circle(5.0);

string result = shape.Match(
    radius => $"Circle with radius {radius}",
    (width, height) => $"Rectangle with width {width} and height {height}"
);

Console.WriteLine(result); // Output: Circle with radius 5.0

4. Compare Unions

Union cases can be compared for equality using the auto-generated equality methods. This allows for checking if two unions are the same.

Shape shape1 = Shape.Circle(5.0);
Shape shape2 = Shape.Circle(5.0);

bool areEqual = shape1.Equals(shape2); // true

Upcoming Features

• Pretty printing: A default ToString() implementation for unions that provides a readable representation of union cases.
• JSON serialization/deserialization: Support for JSON (de)serialization via System.Text.Json.
• Struct unions: More efficient unions using structs with effective data layout.

License

This project is licensed under the MIT License - see the LICENSE file for details.