The data-encoding library is no_alloc compatible, you can use e.g. encode_mut.

We could provide a similar trait, which writes into a mutable slice.

Things to keep in mind:

• base-x currently needs alloc. It's used for bases which are not power of two.
• It increases the API surface, currently this library is pretty small, should we change that?
• Can we make it work without making this library hard to use when you don't need no_std and no-alloc compatibility?
• How would it relate to rust-cid? Could we follow the idea of rust-multihash and use GenericArray when converting into a certain Multibase? Given that we know the maximum digest size of the CID, we also know the possible maximum base encoded size at compile time. Can this be wrapped in a nice to use API?