Functional Extensions for C#

This library helps write code in more functional way. To get to know more about the principles behind it, check out the Applying Functional Principles in C# Pluralsight course.

Installation

Available on nuget

PM> Install-Package CSharpFunctionalExtensions

.NET 4.0 version Installation

.NET 4.0 version is available as a separate package on nuget

PM> Install-Package CSharpFunctionalExtensionsNet4.0

Get rid of primitive obsession

Result<CustomerName> name = CustomerName.Create(model.Name);
Result<Email> email = Email.Create(model.PrimaryEmail);

Result result = Result.Combine(name, email);
if (result.IsFailure)
    return Error(result.Error);

var customer = new Customer(name.Value, email.Value);

Make nulls explicit with the Maybe type

Maybe<Customer> customerOrNothing = _customerRepository.GetById(id);
if (customerOrNothing.HasNoValue)
    return Error("Customer with such Id is not found: " + id);

Compose multiple operations in a single chain

return _customerRepository.GetById(id)
    .ToResult("Customer with such Id is not found: " + id)
    .Ensure(customer => customer.CanBePromoted(), "The customer has the highest status possible")
    .Tap(customer => customer.Promote())
    .Tap(customer => _emailGateway.SendPromotionNotification(customer.PrimaryEmail, customer.Status))
    .Finally(result => result.IsSuccess ? Ok() : Error(result.Error));

Wrap multiple operations in a TransactionScope

return _customerRepository.GetById(id)
    .ToResult("Customer with such Id is not found: " + id)
    .Ensure(customer => customer.CanBePromoted(), "The customer has the highest status possible")
    .WithTransactionScope(customer => Result.Ok(customer)
        .Tap(customer => customer.Promote())
        .Tap(customer => customer.ClearAppointments()))
    .Tap(customer => _emailGateway.SendPromotionNotification(customer.PrimaryEmail, customer.Status))
    .Finally(result => result.IsSuccess ? Ok() : Error(result.Error));

Readings and watchings

• Functional C#: Primitive obsession
• Functional C#: Non-nullable reference types
• Functional C#: Handling failures, input errors
• Applying Functional Principles in C# Pluralsight course

Contributors

A big thanks to the project contributors!

• mnissl
• Vladimir Makaev
• Ben Smith
• pedromtcosta
• Michał Bator
• mukmyash
• azm102
• ThomasDC
• bopazyn
• Joris Goovaerts
• Ivan Deev
• Damian Płaza
• ergwun
• Michael DiLeo
• Jean-Claude
• Matt Jenkins
• Michael Altmann
• Steven Giesel
• Anton Hryshchanka
• Mikhail Bashurov
• kostekk88
• Carl Abrahams
• golavr
• Sviataslau Hankovich
• Chad Gilbert
• Robert Sęk
• Sergey Solomentsev
• Malcolm J Harwood
• Dragan Stepanovic
• Ivan Novikov
• Denis Molokanov
• Gerald Wiltse
• yakimovim
• Alex Erygin
• Omar Aloraini