Notices by Noah Gibbs (codefolio@ruby.social), page 2

@inthehands It's a special value of a different type, so you avoid the whole "nil is a subtype of everything" problem.

In Ruby nil isn't a subtype of everything *and* it has some methods.

So if that's the distinguishing feature of null-as-an-abstraction-across-langs then Ruby's nil isn't one.

@inthehands I'm a little leery of "it's fine, String? is another type, but not a subtype of String" since checking for None looks a lot like checking for nil. But I suppose in a typed language you can at least declare where it's not allowed to be nil, so there's that.

I wanted Rust to be like that, but having unsafe Rust all over limits the advantages pretty heavily (still runtime crashes, for instance.) So I'd need to work on a little-to-no-unsafe-Rust project to know.

@inthehands Yeah, I definitely agree with these criticisms of nil. And yup, adding a special instance for your type-specific special value (linked list node, the symbol :end, etc) is generally much better than nil, for all the reasons you say.

Ruby's doesn't have the same LSP problems (no type declarations => you're not violating a type declaration) but of course nil is still bad.

@inthehands I *am* sorry it ends before he talks about alternatives to null. There are some good ones.

But the Maybe monad is mostly just three nulls in a trenchcoat. It doesn't fix the worst problems with it, it just adds a lot more verbosity to the problem.

Given how fast he was explaining stuff, it *would* have been fascinating to see how he explained monads in 45 seconds 🙂

@inthehands This is a *great* talk.

Major brownie points for mentioning Autocode and Shortcode as early programming langs. Those weren't ones I knew, I'm gonna go learn about them 😃

If you liked my "100-Year Programming Language" article or talk, this talk from Paul Cantrell (@inthehands) at Minnebar is *really* good.

Programming language history, including some wonderful really early stuff.

https://www.youtube.com/watch?v=3aw7777DS58