If you have a background in Python, Java or C++, you're probably used to raising exceptions if something goes wrong. Rust doesn't have exceptions. The official Rust book has a comprehensive chapter on error handling, but the TL;DR is we should probably use the Result type. We can match on its variants to handle both the happy path and error cases in a very explicit, if not verbose, way. To address the verbosity, there was a try! macro that cut down on a lot of pattern matching boilerplate. And as of now we have an even simpler syntax - the ? operator. But when there are many error types, possibly coming from different libraries, making them compose well still requires a lot of code: From and Error implementations and such.

The error_chain crate was created to avoid all that remaining boilerplate. Let's see it in action!