Rustly 10.0.2

Rustly (v10.0.2)

Rust-inspired Result<T, E>, Option<T>, and Unit types for C#. Replace exceptions with explicit, composable error handling. Zero-allocation value types.

All types and helpers are auto-imported when you add the package — no using statements needed.

Installation

dotnet add package Rustly --version 10.0.2

Types

Usage

Result<T, E>

Result<int, string> Divide(int a, int b) =>
    b == 0 ? Err<int, string>("Division by zero") : a / b;  // implicit T → Ok

var result = Divide(10, 2);

// Pattern matching
string message = result.Match(
    ok: value => $"Result: {value}",
    err: error => $"Error: {error}"
);

// Chaining
var doubled = Divide(10, 2)
    .Map(x => x * 2)
    .UnwrapOr(0);

// Composition
var final = Divide(10, 2)
    .AndThen(x => Divide(x, 3))
    .MapErr(e => $"Pipeline failed: {e}");

// Querying
bool isPositive = Divide(10, 2).IsOkAnd(x => x > 0);
bool isBadInput = Divide(10, 0).ContainsErr("Division by zero");

Result<Unit, E> (void operations)

Result<Unit, string> SaveFile(string path)
{
    // ... operation ...
    return Unit.Value;  // implicit Unit → Ok
}

SaveFile("/tmp/data.txt")
    .InspectErr(e => Console.WriteLine($"Save failed: {e}"));

Option<T>

Option<string> FindUser(int id) =>
    id == 1 ? Some("Admin") : None<string>();

// Safe access
string name = FindUser(1).UnwrapOr("Unknown");

// Chaining
var greeting = FindUser(1)
    .Map(n => $"Hello, {n}!")
    .UnwrapOr("Hello, stranger!");

// Filtering
var admin = FindUser(1).Filter(n => n == "Admin");

// Convert to Result
Result<string, string> r = FindUser(42).OkOr("User not found");

// Pattern matching
FindUser(42).Match(
    some: user => $"Found: {user}",
    none: () => "Not found"
);

Combining

// Zip two options
var pair = Some(1).Zip(Some("hello"));  // Some((1, "hello"))

// Flatten nested types
Option<Option<int>> nested = Some(Some(42));
Option<int> flat = nested.Flatten();  // Some(42)

// Transpose
Option<Result<int, string>> optRes = Some(Ok<int, string>(42));
Result<Option<int>, string> resOpt = optRes.Transpose();  // Ok(Some(42))

// Xor
var a = Some(1);
var b = None<int>();
var x = a.Xor(b);  // Some(1) — exactly one is Some

API Reference

Result<T, E>

Option<T>

Prelude (auto-imported)

License

MIT