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HomeiOS DevelopmentSwift wants a greater language reference – Ole Begemann

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 wish to reiterate one level I made then: the Swift venture sorely wants a searchable, linkable language reference.

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

TSPL just isn’t searchable

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

  • Looking for key phrases (if, case, the place) should reliably discover the documentation for the key phrase as the highest consequence. 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 when you might seek for a logo akin to # and it might present you a listing of all syntax components that use this image. This might be very informative and an effective way to discover the language, not only for freshmen — particularly with good IDE integration (see beneath). Swift is such a giant and sophisticated 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 just isn’t linkable

Pages in TSPL are usually 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, akin to @resultBuilder, is tough if you already know your means round HTML and just about unimaginable when 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 midst 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 positioning has no search operate): TSPL is likely one of the high outcomes for swift resultbuilder on Google, however it drops you on the high of the superlong web page on Attributes, with no indication the place to seek out the knowledge you’re in search of.

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

TSPL is structured unsuitable

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

IDE integration

I used to be cautious to make this a criticism concerning the documentation for Swift and never concerning the (equally poor) state of Apple’s developer documentation. Swift just isn’t restricted to app improvement for Apple gadgets, and I imagine it’s important for Swift to place itself as a standalone venture if it desires 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 unsuitable to host the Swift API documentation on

However as soon as we’ve got this language reference, Apple ought to after all combine it into Xcode for offline search and context-sensitive assist. Think about when 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 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, non-compulsory chaining, Elective sample matching, strive?).
  • Clicking on /// would checklist 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 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 in search of.

And this mockup exhibits the way it could possibly 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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