SoftwareMadeSimple.SimpleResults.Functional 1.0.0

SimpleResults.Functional

Functional applicative extensions for SoftwareMadeSimple.SimpleResults, providing Lift and Apply with error accumulation.

Installation

dotnet add package SoftwareMadeSimple.SimpleResults.Functional

Why?

When validating multiple fields independently, you typically want to collect all errors rather than short-circuiting on the first failure. The applicative pattern enables exactly this � validate each field separately, then combine the results while accumulating every error.

Usage

Lift & Apply

Use Lift to wrap a function into a Result, then chain Apply calls to feed in each validated argument. If any argument fails, all errors are accumulated.

using SoftwareMadeSimple.SimpleResults;
using SoftwareMadeSimple.SimpleResults.Functional;

record Person(string Name, int Age);

Result<string, ValidationErrors> nameResult = ValidateName(input.Name);
Result<int, ValidationErrors> ageResult = ValidateAge(input.Age);

var result =
    LiftResult<ValidationErrors>
        .Lift((string name, int age) => new Person(name, age))
        .Apply(nameResult)
        .Apply(ageResult);

if (result.IsSuccess)
{
    Person person = result.Value;
    // use person
}
else
{
    IEnumerable<ValidationError> errors = result.Error;
    // all validation errors are collected here
}

Error accumulation

Unlike monadic Bind (which short-circuits on the first error), Apply runs every validation and collects all failures:

Result<string, ValidationErrors> nameResult = new List<ValidationError>
{
    new("Name is required"),
    new("Name must be at least 2 characters")
};

Result<int, ValidationErrors> ageResult = new List<ValidationError>
{
    new("Age must be positive")
};

var result =
    LiftResult<ValidationErrors>
        .Lift((string name, int age) => new Person(name, age))
        .Apply(nameResult)
        .Apply(ageResult);

// result.Error contains all 3 validation errors

Functions with more parameters

Lift supports functions with up to 16 parameters. Each additional parameter is applied with another .Apply() call:

record Address(string Street, string City, string Zip);

var result =
    LiftResult<ValidationErrors>
        .Lift((string street, string city, string zip) => new Address(street, city, zip))
        .Apply(streetResult)
        .Apply(cityResult)
        .Apply(zipResult);

Requirements

• .NET 10+
• SoftwareMadeSimple.SimpleResults 1.1.0+

License

MIT