> On 25 Feb 2017, at 00:56, Jordan Rose via swift-evolution > <[email protected]> wrote: > > I don't have a good answer for this, but I'll vote against 'foo(:)' because > that's what a lot of people think the name of 'foo(_:)' should be. I'd rather > be able to offer fix-its for that even when you have both 'foo()' and > 'foo(_:)' defined. I'd rather go with 'foo(_)' despite the tiny ambiguity in > pattern contexts. > > (I'm personally in favor of killing unapplied function references altogether > in favor of closures, on the grounds that they are overly terse, make > type-checking more complicated, and often lead to retain cycles. Then we'd > only need this for #selector, and it's perfectly unambiguous to use 'foo()' > there. But I wasn't planning to fight that particular battle now, and it is > rather annoying to require the 'as' in the meantime.)
It is potentially going to be hard to fight that battle. I think a lot of functional/Haskell people love them and would be sad to see them go away (I plead guilty). But it isn’t a well known part of the language so I don’t think the general community would miss it. > Jordan > > >> On Feb 21, 2017, at 23:05, Jacob Bandes-Storch <[email protected] >> <mailto:[email protected]>> wrote: >> >> Evolutioniers, >> >> 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. >> >> To kick off the discussion, I'd like to propose foo(:) for nullary functions. >> >> Advantages: >> - the colon marks a clear similarity to the foo(bar:) form when argument >> labels are present. >> - cutely parallels the empty dictionary literal, [:]. >> >> Disadvantages: >> - violates intuition about one-colon-per-argument. >> - the parallel between #selector(foo(:)) and @selector(foo) is not quite as >> obvious as between #selector(foo(_:)) and @selector(foo:). >> >> >> For the sake of discussion, another option would be foo(_). This was my >> original choice, and I like that the number of colons matches the number of >> parameters. However, it's a little less obvious as a function reference. It >> would preclude _ from acting as an actual identifier, and might conflict >> with pattern-matching syntax (although it appears functions can't be >> compared with ~= anyway). >> >> >> Looking forward to everyone's bikeshed color ideas, >> Jacob > > _______________________________________________ > swift-evolution mailing list > [email protected] > https://lists.swift.org/mailman/listinfo/swift-evolution
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