Support for ECMAScript 'do'-expressions

[CodySchaaf]

Sorry if this has been discussed but it is hard to search for such a generic combination of words.

Is there any plan to implement support for https://github.com/tc39/proposal-do-expressions http://wiki.ecmascript.org/doku.php?id=strawman:do_expressions

It would be awesome to be able to avoid the extra code required when wrapping an if statement in a function to get a dynamic return value.

Thanks!

[aluanhaddad]

These could be quite pleasant to use but unfortunately the proposal is still at Stage 0 in TC39.

[zpdDG4gta8XKpMCd]

I wish it was haskell's do notation

[geverges-oleg]

+1

[steve8708]

looks like this is now in TC39 stage 1 🎉

[zheeeng]

+1 @aluanhaddad What's the accepting standard for ex-next? Is stage 2+ or stage 1 is ok?

[aluanhaddad]

TypeScript tends to adopt proposals once they reach stage 3 in TC39.

This is not a hard and fast rule and there are exceptions such as async/await, which turned out really well, and Decorators, which need a massive overhaul.

[IamManchanda]

As discussed in #20743, I think this should be added in typescript now I really feel so :)

Using kotlin for quite some time and similar syntax for this is quite productive

    message = when {
        (age < 18) -> "You are too young to vote"
        (age == 100) -> "Congratulations"
        else -> "You can vote"
    }

[aluanhaddad]

@IamManchanda see proposal-pattern-matching.

[drhumlen]

Any progress on this one?

[vipcxj]

Any progress on this one?
do expression is very very very useful for react project.

[G-Rath]

@vipcxj Please check the stage of the proposal. Currently, it is still at stage-1, meaning it's in the proposal stage.

This means that the syntax is still being drafted, and thus subject to wild changes.

TS doesn't like to adopt TC39 proposals until they're at least candidates (stage 3). Sometimes they'll implement draft (stage 2), but its very rare, and something they're actively trying to avoid.

You should wait until the proposal is at least in draft status before adopting it.

[alamothe]

do expression seems unnatural. Why not just let any statement be an expression, like in Kotlin?

This could be a part of TypeScript itself, so no need to wait on JavaScript proposal. Thoughts?

[xialvjun]

I'm curious about why we need do in do expression, why not just make any statement be an expression...

import h from 'hyperscript';
import o from 'observable';

const root = h('div', {
  const count = o(0);
  [
    h('h1', {title: count}, count),
    h('button', { onclick: e => count(count()+1) }, 'add 1')
  ]
});

document.body.append(root);

[RyanCavanaugh]

Please discuss the proposal in the proposal repo, not here

Thanks!

[avin-kavish]

Is there a way to stop the typescript language server from erroring on do expressions? Asking because I'm using babel to transpile do expressions but the ts language server in the IDE is complaining about it.

[fullofcaffeine]

Is there a way to stop the typescript language server from erroring on do expressions? Asking because I'm using babel to transpile do expressions but the ts language server in the IDE is complaining about it.

I'd like to know about this, too ^