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REslava.Result .NET Functional Error Handling & Zero‑Boilerplate APIs

.NET C# NuGet Version License GitHub contributors GitHub Stars NuGet Downloads Test Coverage Test Suite

The only .NET library that blends functional error handling with compile‑time API generation.

nuget-package-reslava-result GitHub repo

🗺️ See how your Result<T> flows — before it runs. Pipeline Visualization.

Annotate any fluent pipeline with [ResultFlow] and with single-click code action ResultFlow will insert a Mermaid diagram comment so you can visualize every success path, failure branch, and side effect in your pipeline — zero runtime overhead, zero maintenance.

→ ResultFlow

  • Getting Started
    Installation, quick start, and the transformation (70-90% less code).

  • Core Concepts
    Functional programming foundation: Result, composition, async, Maybe, OneOf, validation, and more.

  • ASP.NET Integration Minimal API, MVC, SmartEndpoints, OpenAPI, authorization, and problem details.

  • Safety Analyzers 7 Roslyn diagnostics + 3 code fixes — catch Result<T> and OneOf mistakes at compile time.

  • Architecture & Design How the library is built – SOLID, package structure, and the source generator pipeline.

  • Code examples
    Code examples: Fast APIs, Console and quick code examples.

  • Testing & Quality 3,339+ tests, CI/CD, real‑world impact, and production benefits.

  • Reference
    Version history, roadmap, and API documentation.

  • Community
    Contributing, license, and acknowledgments.

Why REslava.Result?

Zero‑boilerplate APIs, railway‑oriented programming, and source‑generated ASP.NET integration – all in one package.

Feature Comparison

REslava.Result FluentResults ErrorOr LanguageExt
Result<T> pattern ✅ ✅ ✅ ✅
OneOf discriminated unions ✅ (2-6 types) — — ✅
Maybe<T> ✅ — — ✅
ASP.NET source generators (Minimal API + MVC) ✅ — — —
SmartEndpoints (zero-boilerplate APIs) ✅ — — —
OpenAPI metadata auto-generation ✅ — — —
Authorization & Policy support ✅ — — —
Roslyn safety analyzers ✅ — — —
JSON serialization (System.Text.Json) ✅ — — —
Async patterns (WhenAll, Retry, Timeout) ✅ — — —
Domain error hierarchy (NotFound, Validation, etc.) ✅ — Partial —
Validation framework ✅ Basic — ✅
FluentValidation bridge (optional, migration only) ✅ — — —
Pipeline visualization ([ResultFlow]) ✅ — — —
Zero dependencies (core) ✅ ✅ ✅ —

Ready to Transform Your Error Handling?

📖 Start with the Getting Started Guide

⭐ Star this REslava.Result repository if you find it useful!

Made with ❤️ by Rafa Eslava for the developer community

Report Bug • Request Feature • Discussions