Let's say you're doing something with the result of http.Get, because otherwise it makes no sense. In Go, you'd have something like:

    resp, err := http.Get(someURL)
    if err != nil {
        return nil, err
    }
    res, err := DoStuff(resp)
    if err != nil {
        return nil, err
    }
    return res

In Haskelly-Go, you'd do:

    do
        resp <- http.Get(someURL)
        DoStuff(res)

The types of both http.Get and DoStuff would be monadic, and the result of the do block would also be monadic. When you eventually get to the place where the error is significant, you handle it there when "unwrapping" your value from the monad.