[scaleout1]

Yes thats the pattern I ended up using with the help of `custom_error` crate which automates the implementation of `From` for your custom errors. I guess the disconnect for me was that in Java/Scala all custom exceptions extend `Throwable` so types always line up, in rust custom Errors are disjointed so you have to wrap everything yourself to align the types.

[pornel]

`Throwable` in Rust is `dyn std::error::Error`.

If you make your functions return `Box<dyn Error>` (or `failure::Error`), they will all convert out of the box. The `?` operator performs conversion itself. For chains `.map_err(From::from)` does it.