Swift: Things I really wanted that won’t make it

Error and Result types in the standard library, macros, per-target configurations and tests, a fix for namespacing issues due to the lack of a central repository for open-source libraries. The presence/lack of each of these are some of my favorite things about Rust, and it's too bad to see them miss this release of Swift.

The "with" method cascades could be even nicer if they were VB-like, which needed a . prefix.

Example:

   with obj {
       .field = abc;
       xyz = .foo(12);
       .method();
   }

This would have several advantages:

* easy for syntax completion

* can access names that are not in the innermost with-scope

* can access names at outer with-scopes using .. and ... etc

Apple's ability to release a Swift-based SDK that uses "final" and "final" being the default for classes in Swift are completely orthogonal concepts.

Apple could (and should, I think) release future SDKs that use all-final classes and require composition instead of the incredibly fragile base classes that currently make up UIKit and Foundation - they'd just add the "final" keyword.

Since UIKit is inheritance-based currently, in a final-by-default Swift, it would be imported as "subclassable", "nonfinal", or whatever. Nothing would change other than the default for newly-written Swift code.

> Disambiguating SPM Naming Conflicts

Perl 6 did some work on this. I'm not sure if it's fully supported yet, but the design docs[1] go into detail on how it's supposed to work, so it may be worth looking at.

> Method Cascades I suspect you might find disambiguating your method/attribute access easier in your "with" syntax if you make it match what swift appears to do for anonymous variables, use $0. (pardon my unfamiliarity with Swift, I may be mistaken on some obvious things).

E.g. Instead of

    with let task = NSTask() {
        launchPath = "/usr/bin/mdfind"
        arguments = ["kMDItemDisplayName == *.playground"]
        standardOutput = pipe
        launch()
        waitUntilExit()
    }

do

    with let task = NSTask() {
        $0.launchPath = "/usr/bin/mdfind"
        $0.arguments = ["kMDItemDisplayName == *.playground"]
        $0.standardOutput = pipe
        $0.launch()
        $0.waitUntilExit()
    }

That way if you want to use some non-related variabled within the block, or the output of an attribute or method as the input of some other attribute or method, it's not ambiguous.

1: http://design.perl6.org/S11.html#Versioning