Get Started

UnambitiousFx.Functional is a lightweight functional programming toolkit for .NET.

It gives you core building blocks for explicit, composable workflows:

• Result / Result<T> for explicit success-failure flows.
• Maybe<T> for optional values without null checks everywhere.

Packages

dotnet add package UnambitiousFx.Functional

For web APIs:

dotnet add package UnambitiousFx.Functional.AspNetCore

For test assertions with xUnit:

dotnet add package UnambitiousFx.Functional.xunit

Quick Start

using UnambitiousFx.Functional;
using UnambitiousFx.Functional.Failures;

static Result<int> ParsePositiveInt(string input)
{
	if (!int.TryParse(input, out var value))
		return Result.Failure<int>(new ValidationFailure("Input is not a valid integer"));

	if (value <= 0)
		return Result.Failure<int>(new ValidationFailure("Value must be positive"));

	return Result.Success(value);
}

var result = ParsePositiveInt("42")
	.Map(value => value * 2)
	.Ensure(value => value < 100, new ValidationFailure("Value must be less than 100"));

result.Match(
	success: value => Console.WriteLine($"Success: {value}"),
	failure: error => Console.WriteLine($"Failure: {error.Code} - {error.Message}")
);

Design Principles

• Errors are values, not exceptions used for control flow.
• Pipelines are composable through Bind, Map, Ensure, Recover, and Tap.
• APIs are async-friendly with Task and ValueTask overloads.
• Domain intent is explicit in type signatures.

Next Steps

Follow this path from fundamentals to advanced integration:

1. Read Migration from v1 if you are upgrading.
2. Read Result for railway-oriented pipelines.
3. Read Maybe for optional-value flows.
4. Read Failures and Metadata for error modeling and contextual data.
5. Read ASP.NET Core for HTTP mapping and web API integration.
6. Read xUnit for assertion patterns in tests.