promises-spec VS proposal-record-tuple

Today, I tried implementing Promises/A+ from scratch to test my coding skill. In the process, I’ve crafted this guide to share my insights and experiences with those who share a similar interest. Without further ado, let’s dive in.

That made me chuckle.

For those not familiar with the promise design controversy:

http://brianmckenna.org/blog/category_theory_promisesaplus

https://github.com/promises-aplus/constructor-spec/issues/24

https://github.com/promises-aplus/promises-spec/issues/94

If you really want to go down the rabbit hole on this one, start here

Advantage 1, nesting, is the most important here, and it's often the most-overlooked advantage. Overlooking nesting is how Promises in Javascript got to be fundamentally broken.

Have you read the infamous GitHub thread where people tried to fix this before it got finalized? It's quite a trip

1.) JS implementation of Promise is not a monad. See this StackOverflow answer or this GitHub discussion for more details

In this article, we will go over how to implement a basic version of a promise during a FAANG interview. The standard for promise implementation is called A+, but it includes a huge amount of details, making it almost impossible to implement all of them during a one-hour coding interview. Therefore, we will focus on implementing a basic variation that should be enough to show the interviewer your solving skills.

Hey, at least you weren't these guys: https://github.com/promises-aplus/promises-spec/issues/94

Total carnage

relevant issue, which is at the crux of this problem: https://github.com/tc39/proposal-record-tuple/issues/387

There are still so many basic things that aren't in the JS stdlib, though. A good example is Map - if you need to use a tuple of two values as a key, you're SOL because there's no way to customize key comparisons. Hopefully we'll get https://tc39.es/proposal-record-tuple/ eventually, but meanwhile languages ranging from C++ to Java to Python have had some sensible way to do this for over 20 years now.

If you’re reaching for structuredClone, what you really want is native immutable Record and Tuple syntax, and the companion “deep path properties” syntax which allows for efficient and ergonomic immutable updates:

- https://github.com/tc39/proposal-record-tuple

It will be called "record" in JavaScript which will swing the popularity back the other way I guess (currently a language proposal)

I suspect considering the strong desire to maintain consistency with JavaScript, we will eventually see something that when the Record proposal passes through tc39

I hope the Record and Tuple proposal makes it through

I mean, I'd love some real immutable/persistent data structures in JS by default, or even some Immer-like syntax sugar. Something like the record/tuple proposal would be awesome.

This will become very useful once Records and Tuples are a thing, because it allows you to store object references in a record/tuple (which by definition can only contain primitives).

Record and tuple is at stage 2

Also, js has an ongoing immutable value data types proposal.