Everything looks good to me. Just one thing:

I've also added named_type_derive dependency in named_type such that users of this crate will need to only add named_type dependency in cargo.
Without doing that users were forced to use named_type and named_type_derive and to ensure that both were defined with the same version.

I don't have any problem with this, but if both named_type and named_type_derive have the same version, I don't think I can push them both to crates.io. One of them will have a dependency for a version which doesn't yet exist, since I push them to crates.io serially. I don't know if it's possible to push both versions in parallel, but I'll look into it. It's possible the cargo workspace helps with this, and last time I tested it that wasn't in place. I'm busy tonight, but I'll see if I can get it to work tomorrow!

@cjhowe7 Happy to revert the last commit so this could be unlocked and eventually revisit it later.

btw checking https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html#specifying-path-dependencies looks like it would eventually be possible defining a path dependency but in order to make it upload-able it requires also a valid version that will be then fetched from crates.io

So it should be something like

# named_type/Cargo.toml
version = "xxx"
[dependencies]
named_type_derive = { path = "../named_type_derive", version = "xxx" }

it will require some synchronisation as named_type_derive needs to be upload before named_type

@cjhowe7 any update on this?

Oh my bad, I forgot about this. Just tested this locally, I think everything looks good. Merging now.

No problem :) thanks a lot for merging it

Published in https://crates.io/crates/named_type/0.2.0