Now that escaping with \ has been proposed for KeyPaths, this makes me wonder whether it would be appropriate to use "\foo()" rather than "foo(_)"/"foo(:)" ? It still feels a bit strange, as \foo() looks like escaping the *result* of a call.
On Sat, Feb 25, 2017 at 1:43 PM, David Hart <[email protected]> wrote: > > 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]> 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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