Rough idea for a revision of ruma-api (using generic parameters instead of associated types)

endpoint_v2.rs

pub trait Endpoint<RQ, RS, S> where RQ: BuildRequest, RS: BuildResponse<S> {
    fn build_request() -> RQ;
    fn build_response() -> RS;
    fn info() -> Info;
}

pub struct Info {
    pub description: &'static str,
    pub name: &'static str,
    pub rate_limited: bool,
    pub request_method: Method,
    pub requires_authentication: bool,
    pub router_path: &'static str,
}

pub trait BuildRequest {
    fn body<T>(&self) -> Option<T> where T: Deserialize + Serialize;
    fn headers(&self) -> Option<HashMap<&'static str, String>>;
    fn path<T>(&self) -> Option<T> where T: Deserialize + Serialize;
    fn query<T>(&self) -> Option<T> where T: Deserialize + Serialize;
}

pub trait BuildResponse<S> {
    fn body<T>(&self) -> T where T: Deserialize + Serialize;
    fn headers(&self) -> Option<HashMap<String, String>>;
    fn status(&self) -> S;
}