Robotico.Result

Industry-standard Result and error types for .NET 8 and .NET 10. Railway-oriented, immutable, zero package dependencies (no NuGet dependencies when you install). Trim-friendly; no reflection on hot paths.

Features

• Result types: Result (void), Result<TData>, Result<TData, TError> — all readonly struct
• Industry naming: Map, Bind, MapError (no LINQ-style Select)
• Pattern matching: Match(onSuccess, onError) for all three result types (void, Result<TData>, Result<TData, TError>)
• Side effects: Tap, TapError, TapAsync, TapErrorAsync (void and both generic variants)
• Recovery: Recover, RecoverWith, RecoverAsync; void and typed results have RecoverWith(fallback) (value or full result fallback)
• Validation: Ensure(predicate, errorFactory) for Result<TData> and Result<TData, TError>
• Aggregation: Collect, Sequence, ChooseSuccessful
• Combining: Combine(r1, r2) … Combine(r1, r2, r3, r4) (tuples); Combine(results) for N results of same type → Result<ImmutableArray<T>>
• Exception boundary: Try, TryAsync, ExpectSuccess, ResultErrorException<TError>
• Errors: IError, Error, SimpleError, ValidationError, ExceptionError, DomainError<TCode>, AggregateError
• ValidationError: Result.ValidationError(errors), ValidationError.ForField(name, message); use Result.Error<TData>(validationError) for a result
• Explicit conversions: Result.FromVoid(r), Result.From(r), Result.FromWithIError(r) to convert between result types (no implicit operators; CA1000/CA2225 compliant)
• Task extensions: MapAsync, BindAsync, MapErrorAsync, MatchAsync, TapAsync, TapErrorAsync, RecoverWithAsync, GetValueAsync, ExpectSuccessAsync

Installation

dotnet add package Robotico.Result

Quick start

using Robotico.Result;
using Robotico.Result.Errors;

// Success / error
Result<int> ok = Result.Success(42);
Result<int> err = Result.Error<int>(new SimpleError("Something went wrong"));

// Map / Bind
Result<string> mapped = ok.Map(x => x.ToString());
Result<int> bound = ok.Bind(x => ParseUserId(x));

// Match
string message = result.Match(
    v => $"Value: {v}",
    e => $"Error: {e.Message}");

// Recover
Result<int> safe = result.RecoverWith(0);

// Try (exception → Result)
Result<int> r = ResultUtilities.Try(() => int.Parse(input));
Result r2 = ResultUtilities.TryAsync(async () => await client.SendAsync());

Choosing a result type

• Result — No success value (e.g. save, delete). Success or error only.
• Result<TData> — Success carries a value; errors are IError. Use when callers don't need a specific error type.
• Result<TData, TError> — Success + value and a strongly typed error (e.g. ValidationError, DomainError<TCode>). Use when callers switch on or handle specific error types.

See the design doc (docs/design.adoc) for full guidance.

Documentation

Detailed architecture and design docs (AsciiDoc + Mermaid) are in the docs/ folder:

• Architecture (docs/architecture.adoc) — Type hierarchy, data flow, exception boundary (with Mermaid diagrams).
• Design (docs/design.adoc) — Design principles, when to use which type, API naming.
• Trim and AOT (docs/trim-aot.adoc) — Trim-friendly and AOT-compatible; no reflection on hot paths.

To build HTML from the AsciiDoc sources (e.g. with Asciidoctor):

asciidoctor docs/index.adoc -o docs/index.html
asciidoctor docs/architecture.adoc -o docs/architecture.html
asciidoctor docs/design.adoc -o docs/design.html
asciidoctor docs/trim-aot.adoc -o docs/trim-aot.html

Versioning

We follow Semantic Versioning. Version 1.0.0 is the first stable release. No breaking changes in minor/patch versions.

Building, testing, and benchmarks

From the repo root:

dotnet restore
dotnet build -c Release
dotnet test tests/Robotico.Result.Tests/Robotico.Result.Tests.csproj -c Release

With coverage (Coverlet):

dotnet test tests/Robotico.Result.Tests/Robotico.Result.Tests.csproj -c Release --collect:"XPlat Code Coverage"

Optional CI gate (fail if line coverage below threshold):

dotnet test tests/Robotico.Result.Tests/Robotico.Result.Tests.csproj -c Release --collect:"XPlat Code Coverage" /p:CollectCoverage=true /p:Threshold=90 /p:ThresholdType=line

Run benchmarks (BenchmarkDotNet):

dotnet run -c Release -p benchmarks/Robotico.Result.Benchmarks/Robotico.Result.Benchmarks.csproj -- --filter "*"

Or open robotico-results.slnx in your IDE and build from there.

License

See repository license file.