Result Types

Inspiration

Result types in Oxide are an implementation of what is usually called the Either monad.

However, as in the case of option types, Result<T, E> is inspired by Rust's Result<T, E> API, due to its ergonomics and humanistic terminology.

APIs should return Result<T, E> whenever errors are recoverable, or error propagation is desired. Rust uses them primarily for I/O in the std crate, but they are richly integrated into the ecosystem.

The primary approach to consuming them in Rust is via pattern matching. Unfortunately, C#'s pattern matching is not quite as strong, but additional API provided by Oxide's Result types means that we can use it anyway, with some help from the when clause.

As usual, see the samples for demo code.

Why Result Types

Result types provide for natural chaining of operations, where any operation in the chain can fail, while preserving the original error at the end. Scott Wlaschin of F# for Fun And Profit refers to this as railway oriented programming.

Result types allow this for both synchronous operations, as well as asynchronous ones, including handy helpers for sanely chaining Task<Result<T, E>> without the syntactic horror of nesting await calls.