Sure, in some cases you want to wrap the error type - Rust handles this by essentially having you create a custom error type which is an enum (which can be done

Sure, in some cases you want to wrap the error type - Rust handles this by essentially having you create a custom error type which is an enum (which can be done via macros like quick-error and error-chain), and implementing From<BarError> on it which'd create your custom error type from the BarError. This trait is used by both the try!() macro and the ? operator (which do much the same thing, the latter being the updated syntax): let foo = bar()?; If you need to do something custom in converting bar()'s error into your error type - which is rare - you can use .map_err() like this: let foo = bar().map_err(|e| MyError::BarError(e, extraContext))?;