[swift-evolution] [Pitch] Improving capturing semantics of local functions

Slava Pestov spestov at apple.com
Wed Nov 15 00:01:24 CST 2017

> On Nov 14, 2017, at 6:56 PM, Howard Lovatt via swift-evolution <swift-evolution at swift.org> wrote:
>   2. Allow closures when assigned to a function type to be:
>       2a. Recursive.

Local functions can also be mutually recursive:

func f() {
  func foo() { bar() }
  func bar() { foo() }

This would not work with let bindings, which are not visible before the location where they are defined.

>       2b. Annotatable with:
>             2bi.  @inline

Neither closures nor local functions benefit from being annotated with @_inlineable, because they can only be referenced from inside their defining function, and not across module boundaries. So the optimizer can already inline the function or closure if needed.

>             2bii. @escaping
>       2c. Generic.

See my other response to this thread.

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