[swift-evolution] [Discussion] Here we go again: Extension Functions

Stephen Celis stephen.celis at gmail.com
Fri Feb 26 11:32:34 CST 2016

> On Feb 26, 2016, at 7:21 AM, Pierre Monod-Broca via swift-evolution <swift-evolution at swift.org> wrote:
> I'm less convinced by the suggested syntax, to me it feels a bit weird.
> I'm thinking an attribute on the closure's first parameter, for exemple (feel free to suggest other names):
> func with<T>(value: T, body: (bound T) -> ()) -> T {
>     body(value)
>     return value
> }

While I'm not married to `T.() -> ()`, I do like that it:

- Separates the self parameter from the parameter list
- Avoids an additional keyword

We could also try reusing the recently removed curry syntax:

    func with<T>(value: T, body: (T)() -> Void) -> T {
        return value

Given that curried versions of instance methods are available on the class, and given the fact that the instance versions of these methods have a bound `self` (and would likely have an extension function signature), it might make more sense than using dot-notation.


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