aws.rs

#![feature(async_await)]

use failure::{Fail, Error};
use std::future::Future;
use std::pin::Pin;

/// `S3Request` is a trait that specifies:
/// - the service request/response pairing.
/// - the service protocol (json, rest-json, rest-xml, or query)
/// - optionally, additional metadata.
/// - mechanisms of serializing/deserializing this data
/// - where the request should be routed.
/// In summary, S3Request is a trait encodes shows how
/// a Botocore object can be transformer into an `http::Request<hyper::Body>`, 
/// and how the resulting `http::Response<hyper::Body>` can be transformed
/// into a typed Botocore object.
trait AWSResource {
    type Response;
}

struct GetObjectRequest;
struct GetObjectResponse;

#[derive(Fail, Debug)]
#[fail(display = "invalid toolchain name")]
struct GetObjectError;

impl AWSResource for GetObjectRequest {
    type Response = Result<GetObjectResponse, GetObjectError>;
}

type Fut<'a, T> = Pin<Box<dyn Future<Output = T> + Send + 'a>>;

struct S3;
impl S3 {
    fn call<T>(&self, _: T) -> Fut<T::Response>
    where
        T: AWSResource,
    {
        unimplemented!()
    }
}

async fn run() -> Result<(), Error> {
    let s3 = S3;
    let _: GetObjectResponse = s3.call(GetObjectRequest).await?;
    Ok(())
}

fn main() {
    // assume this is spawned to tokio, romio, or https://github.com/rustasync/runtime.
    let _res = run();
}