Expose Never in public API.

[dylanede]

Currently functions returning impl Filter<Extract = ..., Error = warp::never::Never> cannot be written by the user, preventing them from returning irrefutable filters from functions.

[jxs]

have you tried using futures::never::Never? there's an example which uses it :https://github.com/seanmonstar/warp/blob/master/examples/sse.rs#L3
I think the reason warp uses its own Never type is because Infalible doesn't implement std::error::Error.
hmm but since warp implements Reject for Never crate::never::Nevercan maybe be replaced with futures::never::Never

[taiki-e]

I think the reason warp uses its own Never type is because Infalible doesn't implement std::error::Error.

Infalible implements std::error::Error via std::string::ParseError.
rust-lang/futures-rs#1681 (comment)

[jxs]

ah nice then, thanks @taiki-e! I can submit a PR to address this

[dylanede]

@jxs that PR looks like it should solve the problem. Regarding your first suggestion, I can't use a different Never type from warp in the return signature of my function because I am returning the result of warp::any().map(...), which has the error type warp::never::Never.

[jxs]

resolved with #298