Hi,
I very much think the points mentioned in the motivation are worth addressing
(and IMO this is not an area where “maybe the optimizer can be made smarter”
can cut it; I want performance guarantees, not hopes).
> On 11 Oct 2016, at 23:28, Nate Cook via swift-evolution
> <swift-evolution@swift.org> wrote:
[snip]
On a shallow read I like presented approach, except for
> Both the keys and values collections share the same index type as Dictionary.
> This allows the above sample to be rewritten as:
>
> // Using `dict.keys.index(of:)`
> if let i = dict.keys.index(of: "one") {
> dict.values[i].append(1)
> } else {
> dict["one"] = [1]
> }
The asymmetry between the if / else branches seems ugly to me. That is once
obtaining the value “directly” from dict, and once through the values-view. I
don’t have a great solution here, but is is possible to subscript the dict by
its `Index` as well as its `Key`?
```
// Using `dict.keys.index(of:)`
if let i = dict.keys.index(of: "one") {
dict[i].append(1)
} else {
dict["one"] = [1]
}
```
On another note, I’m not sure whether there is a way (or whether it’s even
worth trying) to avoid hashing the key twice when the `else` branch is taken.
Daniel.
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