proposal-iterator-helpers VS proposal-pattern-matching

Shout out to JavaScript massively delaying https://github.com/tc39/proposal-async-iterator-helpers in the 23rd hour.

The proposal seemed very close to getting shipped alongside https://github.com/tc39/proposal-iterator-helpers while basically accepting many of the constraints of current async iteration (one at a time consumption). But the folks really accepted that concurrency needs had evolved, decided to hold back & keep iterating & churning for better.

I feel like a lot of the easy visible mood on the web (against the web) is that there's too much, that stuff is just piled in. But I see a lot of caring & deliberation & trying to get shit right & good. Sometimes that too can be maddening, but ultimately with the web there aren't really re-do-es & the deliberation is good.

Support for new JavaScript features, including Array.fromAsync(), Set methods, and Iterator helpers.

Global iterator type is coming: https://github.com/tc39/proposal-iterator-helpers

But a method named `groupBy` on iterators traditionally means a different thing: https://github.com/tc39/proposal-array-grouping/issues/51#is...

Global iterable type it's too late for, since there's many extant iterables in the language and on the web which don't have it in their prototype chain and can't reasonably be changed.

Very much agreed. The amount of mileage we get from using Spread (literally the ...) alone has been amazing. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe... Iteration helpers is shipping soon, that'll be a huge help (async iteration helpers will be delayed for a while). https://github.com/tc39/proposal-iterator-helpers .

In the olden days, I feel like the codebases I worked on needed to use .apply() multiple times a week, to figure out some creative way of invoking functions. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe... That's all gone now; I'd take even odds that 50% of my team knows .call and .apply.

Chrome 117 is shipping Object.groupBy() and that's gonna be a huge help in eliminating a lot of the last places we end up using lodash. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...

Once this https://github.com/tc39/proposal-iterator-helpers reaches browsers, I'm prob gonna be exclusively using Maps.

No, probably not. But with iterator helpers, you can do

> focus more on improving the terrible JS web API

That's W3C’s job, not ECMA’s.

> Where are all the containers?

?

> Sorted sets/maps?

Sets and Maps are sorted (by insertion order)

> Why can't I even map an iterator?

It's coming, but someone will likely be exhausted by that addition. https://github.com/tc39/proposal-iterator-helpers

Upcoming: https://github.com/tc39/proposal-iterator-helpers

Not Generators, but Iterators have a Stage 3 proposal with helpers like these.

Note, however, that there is a proposal to add pattern matching to JS.

There's an ECMAScript proposal that is in the works to add this feature to the language! It's going to look something like this.

More importantly, TypeScript typically commits to build things into itself when the proposal in JavaScript reaches Stage 3. The pattern matching proposal in JavaScript is Stage 1, but depends on many other proposals as well that may or may not need to be at Stage 3 as well for it to work. This particular proposal is interested on pattern matching on JavaScript Objects and other primitives, just like Python does with it’s native primitives. These are also dynamic types which helps in some areas, but makes it harder than others. Additionally, the JavaScript type annotations proposal needs to possibly account for this. So it’s going to be awhile. Like many years.

For true™ functional programming in JS, native pattern matching and partial function application are missing (at least for now: 1, 2). For proper OOP, it lacks real interfaces and compile-time dependency injection.

The proposal for pattern matching syntax seems more akin to what they're looking for.

https://github.com/tc39/proposal-pattern-matching

There's a proposal to add something like that to JavaScript but it's been stuck in limbo since 2017 although there are libraries like ts-pattern which implement it already.

I'll admit, it is easy to assert that the TypeScript language should not be involved in the matters of packages but I also wonder if we're moving towards a point where interfaces will be as common as namespaces and whether or not it would be sensible for the language to incorporate such type assertions into the language formally, after all, it already compiles to various forms of JavaScript and there is a stage 1 proposal submitted to the TC39 committee to give JavaScript pattern matching. If adopted, wouldn't it make sense to allow TypeScript to compile a type into a type guard for the native JavaScript pattern matcher?

Both are active tc39 proposals :)

https://github.com/tc39/proposal-pipeline-operator - Stage 2

https://github.com/tc39/proposal-pattern-matching - Stage 1

Hopefully we get both in the next couple of years.

We often add promising TC39 proposals into Civet so people can experiment without waiting.

We've added https://github.com/tc39/proposal-pipeline-operator, a variant of https://github.com/tc39/proposal-pattern-matching, a variant of https://github.com/tc39/proposal-string-dedent and others.

Since our goal is to be 99% compatible with ES we'll need to accommodate any proposals that become standard and pick up anything TC39 leaves on the table (rest parameters in any position, etc.)