Visibility of the Stream adaptor structures in tokio-stream

[sharpened-nacho]

The StreamExt trait provides the helpful method take, map, and the like on Streams. But the structures themselves (Take, Map, etc.) are not visible outside the crate, as they are not pub use in stream_ext.rs.
Is there a reason for that?

For context, I am playing around with tonic, and need to name the type of the Stream I use to implement a Server Streaming RPC. So :

impl MyServiceTrait for MyServiceStructure {
    type RpcResponseType = Take<MyStreamType>;

    async fn my_fn(&self, request: ...) -> Result<Response<RpcResponseType>, Status> { ... }
}

and I can't import Take.

[Darksonn]

We usually do this kind of thing so that we can later use impl Trait as the return value in the extension trait without a breaking change. But in the case of tokio-stream this seems less important, as we can just make a breaking change.

[sharpened-nacho]

Sorry, I don't think I understand the explanation :/ Are you referring to changing, say, fn take(self, n: usize) -> Take<Self> to fn take(self, n: usize)-> impl Stream ? In which case I don't get why the visibility of Take has any influence in that, which makes me think I just didn't get it.
As for the 2nd sentence, does it imply some change will be made?

[Darksonn]

If the type is visible, then you can write code that would not compile if the type stops being Take<Self>. Changing it to return impl Stream would count as that.

As for whether a change will be made, well, I could probably be convinced to accept a change for this. But I will not make the change myself.

[sharpened-nacho]

Thank you for clarifying.
I understand the comfort of having the option to change the type, but I must admit I don't see a context for it - I have no experience in maintaining libs though.

I can do the change myself then. I would have asked to - it's a great first issue and PR as it's simple. I will study the contribution guide, make sure I understand everything, and come back in issues.
Thanks for the responses!

[Darksonn]

It's more important for AsyncReadExt where we want to change fn next() -> Read to async fn next() -> usize in the future.