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Swift wants a greater language reference – Ole Begemann

In August 2020, I posted a rant on the Swift boards concerning the poor state of Swift documentation. Nothing got here of it, however I need to reiterate one level I made then: the Swift challenge 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) incorporates a lot of the info I’d anticipate from such a useful resource. However that part isn’t effectively structured to function an precise reference:

TSPL will not be searchable

The TSPL web site doesn’t have a search discipline. Even when it had one, I think about it will be a full-text search over your complete website, as is frequent (and applicable) for a guide. A language reference wants a unique 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 need to see the a whole lot 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 for those who might seek for an emblem reminiscent of # and it will present you an inventory of all syntax components that use this image. This might be very informative and a good way to discover the language, not only for rookies — particularly with good IDE integration (see under). Swift is such an enormous and complicated language that most individuals received’t know each language function.

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 typically lengthy, with many separate objects crammed right into a single web page. For instance, all compiler attributes are documented on a single web page.

Sharing a hyperlink to a particular attribute, reminiscent of @resultBuilder, is troublesome if your method round HTML and just about inconceivable for those who don’t (to not point out the unhealthy 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 if you arrive from a search engine (as most individuals would as a result of the location has no search perform): TSPL is without doubt one of the prime outcomes for swift resultbuilder on Google, however it drops you on the prime of the superlong web page on Attributes, with no indication the place to search out the data you’re on the lookout for.

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

TSPL is structured incorrect

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 grievance concerning the documentation for Swift and never concerning the (equally poor) state of Apple’s developer documentation. Swift will not be restricted to app growth for Apple gadgets, and I consider it’s important for Swift to place itself as a standalone challenge if it needs to be perceived as a viable general-purpose language.

It’s good that TSPL is hosted on and never, and that’s additionally the place this new language reference I’m envisioning ought to stay. (I additionally assume it’s incorrect to host the Swift API documentation on

However as soon as we’ve this language reference, Apple ought to in fact combine it into Xcode for offline search and context-sensitive assist. Think about for those who might Possibility-click not solely identifiers however any token in a supply file to see its documentation.

A couple 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 objective and what you must 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 components that use a query mark (shorthand for Optionals, optionally available chaining, Optionally available sample matching, strive?).
  • Clicking on /// would checklist the magic phrases Xcode understands in doc feedback.

You get the thought. This might be such an enormous assist, not just for rookies.

To summarize, that is the unhappy state of looking for 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 on the lookout for.

And this mockup exhibits the way it may very well 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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