Ole Begemann

The problem is that RSS doesn't really have a concept of "deleted". In general feeds just contain the newest items. Items not on the feed are generally considered old, not deleted.

You can play with heuristics like "This feed is usually sorted by published date and these entries I saw previously should still be here but are missing, maybe they were deleted" but not even have published or updated dates and they aren't always accurate.

This gets even more complicated with WebSub which allows hubs go remove entries they have already seen. So now you need to not do deletion on those requests, and if you turn down your poll rate for feeds with WebSub (which Feedly does IIRC) you might not even fetch the full feed to notice that items are missing for weeks.

The one thing that would actually be reliable here is probably Atom's pagnation and archiving extensions which you can follow to get a view of all of the items in the feed and prune missing ones. However you probably don't want to do this every fetch (otherwise it kinda defeats the point of pagnation). Maybe you could combine this with other heuristics to come up with a decent system. But I'm not even sure these have ordering guarantees so I'm not sure if you are going to fetch potentially unlimited pages just to check if an item was deleted.

If we did want to solve this problem the best option would probably be to add a tombstone element to the feed to explicitly remove items.

TL;DR as far as I am aware neither RSS or…

> Swift’s string implementation goes to heroic efforts to be as Unicode-correct as possible. […] This is great for correctness, but it comes at a price, mostly in terms of unfamiliarity; if you’re used to manipulating strings with integer indices in other languages, Swift’s design will seem unwieldy at first, leaving you wondering.

> It’s not that other languages don’t have Unicode-correct APIs at all — most do. For instance, NSString has the enumerateSubstrings method that can be used to walk through a string by grapheme clusters. But defaults matter; Swift’s priority is to do the correct thing by default.

> Strings in Swift are very different than their counterparts in almost all other mainstream programming languages. When you’re used to strings effectively being arrays of code units, it’ll take a while to switch your mindset to Swift’s approach of prioritizing Unicode correctness over simplicity.

> Ultimately, we think Swift makes the right choice. Unicode text is much more complicated than what those other languages pretend it is. In the long run, the time savings from avoided bugs you’d otherwise have written will probably outweigh the time it takes to unlearn integer indexing.

— https://oleb.net/blog/2017/11/swift-4-strings/

Here's what Chris Lattner said about Kotlin this past June:

"Lattner: Swift and Kotlin evolved at about the same point in time with the same contemporary languages around them. And so the surface-level syntax does look very similar. … But if you go one level down below the syntax, the semantics are quite different. Kotlin is very reference semantics, it’s a thin layer on top of Java, and so it perpetuates through a lot of the Javaisms in its model.

"If we had done an analog to that for Objective-C it would be like, everything is an NSObject and it’s objc_msgSend everywhere, just with parentheses instead of square brackets. And a lot of people would have been happy with that for sure, but that wouldn’t have gotten us the functional features, that wouldn’t have gotten us value semantics, that wouldn’t have gotten us a lot of the safety things that are happening [in Swift].

"I think that Kotlin is a great language. I really mean that. Kotlin is a great language, and they’re doing great things. They’re just under a different set of constraints."

https://oleb.net/blog/2017/06/chris-lattner-wwdc-swift-panel/

> I think many also find its syntax more approachable compared to that of Rust.

Chris Lattner (of LLVM fame) did design the language with the goal of hiding complexity until it is needed.

> The concept of progressive disclosure in Swift, where you can start with something very simple and then learn complexity as you go, was totally driven by making it teachable. I personally spent a lot of time trying to make sure that the introduction to Swift could just be print("Hello World"). No semicolons, no \ns, none of that public static void main stuff. Making it simple and approachable was a strong goal, and not in a weird way where in a teaching environment there is this “Swift Prime” language that’s similar but different.

https://oleb.net/blog/2017/06/chris-lattner-wwdc-swift-panel/

When I wanted to code a foundation of reusable code for different devices I would either do it like Dropbox and use C++ as the most common layer http://oleb.net/blog/2014/05/how-dropbox-uses-cplusplus-cross-platform-development/ or use Javascript (which I can also use for web pages) for the program logic like described here http://www.skyscanner.net/blogs/developing-mobile-cross-platform-library-part-3-javascript

Also interesting http://kivy.org allows you to use Python for iOS, Android, OS X and Windows.

I would not bet on Swift and cross compiling it today... too bleeding edge. But interesting project... hope it matures. Good luck!

Call it a database if you wish. In fact it is probably sqlite running behind the scenes.
It is a relational model, a different way of organizing things compared to the hierarchical model of the filesystem. There is probably enough literature about that to fill your ebook library ;)

I suppose that the "library" model is what most people prefer since most modern media apps use that in some form or another. Or maybe it is because of Steve Jobs reality distortion field ( https://oleb.net/blog/2012/06/steve-jobs-on-the-file-system/ ). Still, I hate all these apps attempting to hide the filesystem from me.