bfriesen/randomskunk.results

A functional alternative to exception-based error handling in C#.

RandomSkunk.Results

Two things that make code harder to reason about are exceptions and null. The libraries in this repository aim to do something about exceptions by providing "result" structs to explicitly represent what happened during an operation that could potentially fail. To address null, these results don't accept null as any sort of input and don't provide null from any output^***.

There are three types of results:

• Result
  • For operations that can fail and do not have a return value.
  • Can be either:
    • Success, or
    • Fail with a non-null Error object.
• Result<T>
  • For operations that can fail and have a return value which is always provided.
  • Can be either:
    • Success with a non-null value, or
    • Fail with a non-null Error object.
• Maybe<T>
  • For operations that can fail and have a return value which may or may not be provided.
  • Can be one of:
    • Success with a non-null value,
    • Fail with a non-null Error object, or
    • None indicating no value.

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There are a number of libraries in this repository: the main library, and several that depend on the main library and provide result functionality in specific domains.

RandomSkunk.Results

The main library. Implementations of the Result monad.

RandomSkunk.Results.AspNetCore

Using RandomSkunk.Results from AspNetCore apps.

RandomSkunk.Results.Dapper

Using RandomSkunk.Results with Dapper.

RandomSkunk.Results.Http

Using RandomSkunk.Results with System.Net.Http and System.Net.Http.Json.

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Example Project

The solution in this repository contains an example Blazor Web Assembly app that demonstrates how to use the RandomSkunk.Result libraries. To run the app, select the ExampleBlazorApp.Server project as the startup project.

These are the interesting parts of the example app (with links to the code):

• ExampleBlazorApp.Client project
  • Typed HTTP Clients - each one uses RandomSkunk.Results.Http to make HTTP requests to the server
    • WeatherForcastClient
    • WeatherProfileClient
      • GetWeatherProfiles
      • AddWeatherProfile
      • EditWeatherProfile
  • Razor pages - each one uses one of the typed HTTP clients to make a request to the server, then handles the result
    • FiveDayForecast
    • WeatherProfiles
      • FetchWeatherProfiles
      • SaveProfile
• ExampleBlazorApp.Server project
  • WeatherRepository - uses RandomSkunk.Results.Dapper to make queries to the database
    • GetMonthlyTemperature
    • GetWeatherProfiles
    • UpsertWeatherProfile
  • WeatherForecastSimulator - uses WeatherRepository to make queries to the database
  • Controllers
    • WeatherForecastController - uses WeatherForecastSimulator to simulate weather forecasts
    • WeatherProfilesController - uses WeatherRepository to make queries to the database
      • GetWeatherProfiles
      • AddWeatherProfile
      • EditWeatherProfile