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0 pointsSpiritus7y ago0 comments

That's nice and all. But then you have abominations like this:

    state
        .db
        .send(Queries::GetTopTenHottestYears)
        .from_err()
        .and_then(move |res| {
            result.push(res.unwrap());
            state
                .db
                .send(Queries::GetTopTenColdestYears)
                .from_err()
                .and_then(move |res| {
                    result.push(res.unwrap());
                    state
                        .db
                        .send(Queries::GetTopTenHottestMonths)
                        .from_err()
                        .and_then(move |res| {
                            result.push(res.unwrap());
                            state
                                .db
                                .send(Queries::GetTopTenColdestMonths)
                                .from_err()
                                .and_then(move |res| {
                                    result.push(res.unwrap());
                                    fut_ok(result)
                                })
                        })
                })
        })
        .and_then(|res| Ok(HttpResponse::Ok().json(res)))
        .responder()

https://github.com/actix/examples/blob/master/async_db/src/m...

My suspicion is the people do this to avoid "variable does not live long enough" type errors.

0 comments

3 comments · 3 top-level

gamegoblin7y ago

I believe that is written that way because it's using futures. Once async/await lands this year, all of the futures combinator madness goes away.

thibran7y ago

The code could use closures to split the expression or define local functions on the bottom of the surrounding function (a.k.a Haskell style). This would increase readability a lot.

Example: https://play.rust-lang.org/?gist=7ea1a39971399d0429f0369cb9e...

drudru117y ago

This is called the 'pyramid of doom' in the nodejs circles

j / k navigate · click thread line to collapse

state .db .send(Queries::GetTopTenHottestYears) .from_err() .and_then(move |res| { result.push(res.unwrap()); state .db .send(Queries::GetTopTenColdestYears) .from_err() .and_then(move |res| { result.push(res.unwrap()); state .db .send(Queries::GetTopTenHottestMonths) .from_err() .and_then(move |res| { result.push(res.unwrap()); state .db .send(Queries::GetTopTenColdestMonths) .from_err() .and_then(move |res| { result.push(res.unwrap()); fut_ok(result) }) }) }) }) .and_then(|res| Ok(HttpResponse::Ok().json(res))) .responder()