[swift-evolution] Pitch: Compound name `foo(:)` for nullary functions

Ben Rimmington me at benrimmington.com
Thu Feb 23 07:59:49 CST 2017


> On 22 Feb 2017, at 07:05, Jacob Bandes-Storch wrote:
> 
> Compound name syntax — foo(_:), foo(bar:), foo(bar:baz:) — is used to disambiguate references to functions. (You might've used it inside a #selector expression.) But there's currently no compound name for a function with no arguments.
> 
>     func foo() {}  // no compound syntax for this one :(
>     func foo(_ bar: Int) {}  // foo(_:)
>     func foo(bar: Int) {}  // foo(bar:)
>     func foo(bar: String, baz: Double) {}  // foo(bar:baz:)
> 
> Given these four functions, only the first one has no compound name syntax. And the simple reference "let myfn = foo" is ambiguous because it could refer to any of the four. A workaround is to specify a contextual type, e.g. "let myfn = foo as () -> Void".
> 
> I filed SR-3550 <https://bugs.swift.org/browse/SR-3550> for this a while ago, and there was some discussion in JIRA about it. I'd like to continue exploring solutions here and then write up a formal proposal.

Would the following be an option?

	 foo()  // Function call expression.
	`foo()` // Function reference (using backticks).

-- Ben

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