Swift wants a greater language reference – Ole Begemann


In August 2020, I posted a rant on the Swift boards in regards to the poor state of Swift documentation. Nothing got here of it, however I wish to reiterate one level I made then: the Swift undertaking sorely wants a searchable, linkable language reference.

To be truthful, Swift does have a language reference: the eponymous part in The Swift Programming Language (TSPL) comprises many of the info I’d count on from such a useful resource. However that part isn’t properly structured to function an precise reference:

TSPL will not be searchable

The TSPL web site doesn’t have a search subject. Even when it had one, I think about it could be a full-text search over the complete web site, as is widespread (and applicable) for a ebook. A language reference wants a distinct search engine:

  • Trying to find key phrases (if, case, the place) should reliably discover the documentation for the key phrase as the highest end result. I don’t wish to see the a whole bunch of pages that include the phrase “if” of their physique textual content.

  • I’d love to have the ability to seek for punctuation. Think about in the event you might seek for a logo corresponding to # and it could present you a listing of all syntax parts that use this image. This might be very informative and a good way to discover the language, not only for freshmen — particularly with good IDE integration (see under). Swift is such a giant and complicated language that most individuals gained’t know each language characteristic.

A language reference wants a search engine that is aware of to deal with key phrases and punctuation.

TSPL will not be linkable

Pages in TSPL are usually lengthy, with many separate gadgets crammed right into a single web page. For instance, all compiler attributes are documented on a single web page.

Sharing a hyperlink to a selected attribute, corresponding to @resultBuilder, is troublesome if you understand your means round HTML and just about inconceivable in the event you don’t (to not point out the dangerous URL).

As a reader, opening such a hyperlink is disorienting because it drops you in the course of a really lengthy web page, 95 % of which is irrelevant to you.

The reader expertise is even poorer whenever you arrive from a search engine (as most individuals would as a result of the location has no search operate): TSPL is without doubt one of the prime outcomes for swift resultbuilder on Google, nevertheless it drops you on the prime of the superlong web page on Attributes, with no indication the place to seek out the data you’re searching for.

Each language assemble, key phrase, attribute, and compiler directive ought to have its personal, linkable web page.

TSPL is structured improper

The Language Reference part in TSPL is organized as if it was written for parser or compiler builders. It makes use of the language’s grammar as a place to begin and branches out into expressions, statements, declarations, and so forth.

For instance:

I don’t learn about you, however as a consumer of the language, that’s not how I take into consideration Swift or how I seek for documentation.

Along with a superb search engine, a language reference wants an alphabetical index of each key phrase or different syntax ingredient, with hyperlinks to the respective element web page.

IDE integration

I used to be cautious to make this a criticism in regards to the documentation for Swift and never in regards to the (equally poor) state of Apple’s developer documentation. Swift will not be restricted to app growth for Apple units, and I consider it’s important for Swift to place itself as a standalone undertaking if it needs to be perceived as a viable general-purpose language.

It’s good that TSPL is hosted on swift.org and never developer.apple.com, and that’s additionally the place this new language reference I’m envisioning ought to reside. (I additionally suppose it’s improper to host the Swift API documentation on developer.apple.com.)

However as soon as we now have this language reference, Apple ought to in fact combine it into Xcode for offline search and context-sensitive assist. Think about in the event you might Choice-click not solely identifiers however any token in a supply file to see its documentation.

A number of examples:

  • Clicking on if case let would clarify the sample matching syntax.
  • Clicking on in would explains the varied closure expression syntax variants.
  • Clicking on #fileID would present you an instance of the ensuing string and evaluate it to #file and filePath.
  • Clicking on @propertyWrapper would clarify what a property wrapper is and how one can implement one.
  • Clicking on @dynamicMemberLookup would clarify its function and what it’s a must to do to implement it.
  • Clicking on < in a generic declaration would clarify what generic parameters are and the way they’re used.
  • Clicking on ? would present all language parts that use a query mark (shorthand for Optionals, elective chaining, Non-obligatory sample matching, attempt?).
  • Clicking on /// would record the magic phrases Xcode understands in doc feedback.

You get the concept. This might be such a giant assist, not just for freshmen.

To summarize, that is the unhappy state of trying to find language options in Xcode’s documentation viewer:


Xcode documentation viewer showing meaningless results when searching for 'guard'
guardian let me watch youtube else { throw match }

Xcode documentation viewer showing meaningless results when searching for 'associatedtype'
Nope, this isn’t what I used to be searching for.

And this mockup reveals the way it might be:


Mockup of an imagined Xcode documentation popover for #fileID
Sure, I rebuilt Xcode’s documentation popover in SwiftUI for this mockup, syntax highlighting and all.

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