Useful opinionated domain components and/or helper functions for .NET solutions.

Classes and interfaces to help with functional programming in C#.

• NuGet package: ToolPack.DomainUtils.Functional

This is a simple implementation of the Result pattern in C#.

The package contains Result<T> and Result (i.e. Result<Success>) classes, used to represent the result of an operation that can succeed or fail:

• In case of success, the Value property (of type T) will contain the successful output of the operation,
• In case of failure, the Error property will contain the Error output of the operation.

The Error class represents operation errors with all their details.

Useful references:

• The ServiceResult Pattern
• Functional C#: Handling failures, input errors
• Improving API error responses with the Result pattern
• What's the Result Type Everyone Is Using in .NET?

The package contains a set of extension methods to help with the handling of Result instances:

• Execute/ExecuteAsync execute a Result function or action if the input result is successful, or return the initial Error in case of input failure;
• Log methods log the output of the input Result instance, depending on the input result being a success or error;
• Map/MapAsync methods apply functions of generic return type, depending on the input result being a success or error;
• Pipe/PipeAsync methods apply a Result function to the Value of an input Result<T> instance if it is successful, or return the initial Error in case of input failure;
• Switch/SwitchAsync methods run actions, depending on the input result being a success or error.

These methods are useful to chain operations and handle the output of each operation in a functional way.

They intend to help with the implementation of the Railway Oriented Programming (ROP) pattern.

Useful references:

• Railway Oriented Programming
• Functional Programming With C# Using Railway-Oriented Programming Approach
• Handling Side Effects In Functional Code With Railway-Oriented Programming