async/await

[jaydson]

I'm trying to use async/await(es7) (experimental feature in 6to5) but i'm not sure gulp-6to5 is working. I've changed build.js file:

    config: {
        jscs: { configPath: '.jscsrc', esnext: true },
        '6to5': { blacklist: ['generators'], experimental: true },
        mocha: { bail: true, timeout: 5000 }
    }

My sample code:

async function test() {
    let x = await Promise.resolve();
}

And i get the following error: events.js:85 throw er; // Unhandled 'error' event ^ /home/jaydson/Workspace/harmonic/dist/bin/parser.js:19 async function test() { ^^^^^^^^ SyntaxError: Unexpected token function
The async function is not being transpiled.

Any thoughts @UltCombo ?

[jaydson]

I found the issue. It seems like the config property 6to5 in build.js is being ignored. I changed the gulpfile to this:

.pipe(plugins['6to5'], { experimental: true })

instead of this:

.pipe(plugins['6to5'], build.config['6to5'])

and it works.

Probably the blacklisted generators never were blacklisted until now.

[UltCombo]

Probably the blacklisted generators never were blacklisted until now.

Weird. I'm pretty sure co-prompt was throwing errors when we transpiled generators.

It looks like the async functions transform converts them to generators, so the async functions transform doesn't work/is ignored when we blacklist generators. I believe this makes sense, anyway, @sebmck can you confirm?

@jaydson change the build.js to remove generators from the blacklist and enable the experimental option:

'6to5': { experimental: true },

Does this work?

[UltCombo]

If that's the issue, then we can replace co-prompt with Inquirer (#68) then remove generators from the blacklist and use async functions. :smile:

[sebmck]

Async functions and generators are transformed in the same transformer (it's delegated to regenerator). It's confusing I know but since 3.0.0 is going to include a regenerator fork it'll allow it to be split up into multiple transformers.

[UltCombo]

@sebmck oh nice! Thanks for the clarification. :smile:

[jaydson]

@UltCombo both '6to5': { experimental: true } and '6to5': { blacklist: ['generators'], experimental: true } works in the same way.

[UltCombo]

@jaydson I believe blacklist: ['generators'] disables the async transform as @sebmck explained.

Doesn't '6to5': { experimental: true } work? It fails to transpile async functions or throws some specific error?

[jaydson]

Oh, now i got it. '6to5': { experimental: true } works (transpile async functions). We can remove generators from the blacklist :)

[UltCombo]

Oh nice. :)

Btw, the whole idea behind the build.js file is to have project-specific settings outside of the gulpfile, so that whenever we update the gulpfile we can seamlessly copy it to the slush-es6 repository forth and back. This way we can pull updates from slush-es6 by simply copying the files over.

Of course, in the future Harmonic may need a more complex gulpfile than slush-es6's, but for the time being this workflow has been working nicely. :smiley:

[UltCombo]

@jaydson also, please test harmonic init before committing the changes.

IIRC, co-prompt was throwing an error when we passed a transpiled generator to it.

As we've discussed earlier, we can't transpile generators with regenerator as co and co-* libs are not transpiled (they work with native generators only). So I guess we have to drop the co dependency(ies) before un-blacklisting generators.

[UltCombo]

There's probably regenerator'ed versions of co out there, but if we're using it only for the CLI input we can easily replace it with Inquirer and drop co. What do you think?

[jaydson]

I think we can replace co and focus on async/await.

Weird thing is i've tested harmonic init and it worked well. I'm probably missing something.

[UltCombo]

@jaydson perhaps it was an issue with one of our dependencies that got fixed. Never mind it if it is working as expected for you. :D

focus on async/await

:+1:

[jaydson]

We're already using async functions yay! https://github.com/JSRocksHQ/harmonic/commit/c4bb69d0495f6b9d795b1e39075b7f919559fa6b