MonadicTypes.NET 0.3.0-preview.2

MonadicTypes.NET

Allocation-conscious Result<T,E>, Option<T>, Unit, composition, and struct-callable primitives for C# 14 and .NET 10.

Use this core package when expected failure or absence should be represented in the type system without reflection, exceptions for ordinary control flow, or a dependency-injection requirement.

Requirements

• .NET 10 or later
• Compatible with trimming and NativeAOT
• No runtime package dependencies

Install

dotnet add package MonadicTypes.NET --prerelease

Quick Start

using MonadicTypes;

static Result<int, string> ParsePositive(string text) =>
    int.TryParse(text, out int value) && value > 0
        ? Result<int, string>.Ok(value)
        : Result<int, string>.Fail("A positive integer is required.");

string message = ParsePositive("21")
    .Map(static value => value * 2)
    .Match(
        static value => $"Value: {value}",
        static error => $"Error: {error}");

Option<string> name = Option<string>.Some("Ada");
int length = name.Map(static value => value.Length).ValueOr(0);

Core Behavior

• Result<T,E> is exactly Ok(T) or Fail(E); its default value is invalid.
• Option<T> is Some(T) or None; default(Option<T>) is None.
• Equality and hashing inspect only the active Result or Option payload.
• Some(null) is rejected.
• Map transforms success, Bind composes dependent results, and MapError transforms failure.
• Result<Option<T>,E> represents a fallible lookup where absence is expected.
• Combine, Zip, and two-through-six-input Map/Bind compose independent results; caller-state forms avoid captured projection delegates.
• Recover, ValueOrElse, and RequireSome accept caller state when a lazy failure path needs local data without a captured delegate.
• Option.Traverse exchanges optional input with a fallible stage.
• Explicit nullable bridges and deconstruction support application boundaries and patterns.

Normal static callbacks and successful pipelines allocate 0 B in the accepted benchmarks. Caller-state overloads avoid closures, while struct callables are available for measured hot paths. Do not use Result or Option inside parsing or vectorized inner loops where a simpler branch or Try* contract is cheaper.

Related Packages

Documentation

See the complete API guide, API behavior reference, and benchmark policy.

Apache-2.0. Developed with AI assistance.

Complete API reference

Documented public members: 153