> What do you enter as error type in the type signature? In most cases, it would be sufficient to use Box<dyn Error>, but that requires boxing and thus an alloc

> What do you enter as error type in the type signature? In most cases, it would be sufficient to use Box<dyn Error>, but that requires boxing and thus an allocation, which is something that many libraries want to avoid to be useful for no_std or resource-constrained usecases. Okay, so you are in a resource-constrained environment. What would you do in C or C++? You can't do exceptions in C++ here, because there's allocation and other ugliness for embedded or whatever. You can always have your rust code return an int, like we do in C if the boilerplate is too much for you. On the other end, you have Kotlin and Swift Results. Kotlin type-erase the error completely. And I'm pretty sure Kotlin's Result allocates on failure. I'm not sure about Swift. But are you running Swift, with its heap allocated `class` and reference counting on embedded? You're surely not running Kotlin.