CS2 Discussion: Project: Progress as of November 2016

[coffeescriptbot]

From @GeoffreyBooth on 2016-11-04 05:34

Just starting a thread to review where we are, and discuss next steps. So as of 2016-11-12 there has been progress on the jashkenas/coffeescript 2 branch:

• Async/await is implemented, thanks to @GabrielRatener.
• Arrow functions, function default parameters and function rest parameters are implemented, thanks to me.
• Splats in arrays and function calls are output using ES2015 syntax, thanks to @connec.
• Computed properties are output using ES2015 syntax, thanks to @connec.
• Octal and binary literals are output as-is, thanks to @JimPanic.
• CoffeeScript is stricter about whitespace thanks to @eelco, and Literate CoffeeScript now understands Markdown thanks to @billymoon.
• Support for ES2015 for...of is implemented, thanks to @atg.
• Bugs were fixed by @alangpierce, @shreeve, @JimPanic and others. Also thanks for feedback from @lydell and @jashkenas.

I’ve updated our project tracker. I think there’s no question that the top priority on the current list is classes. A lot of progress was made in #4330, but that branch has a lot of broken tests (especially after the arrow-functions PR was merged in) and the last commit was a month ago. @connec, would you appreciate some help with this? Do you still think the approach you took in this PR is the most promising one? Would anyone else be up for helping implement classes?

Update: #4354 is a PR that will hopefully add ES class support.

I think classes are so important that we should release our first alpha of CoffeeScript 2 as soon as classes are supported. We could even approach class support iteratively, perhaps supporting the minimum at first and later on adding back in executable class bodies or whatever other Coffee-only features we’re struggling with.

I think the next-most-important feature, and the only other one that concerns interoperability, is tagged template literals. @greghuc, have you made any progress on this? If so, would you mind pushing a branch somewhere, even if it’s a work in progress? You’re welcome to use https://github.com/GeoffreyBooth/coffeescript if you want a central place for people to collaborate. Is anyone else eager to see tagged template literals supported, and has time to help with this? As part of implementing this, we would implement outputting interpolated strings using ES2015 syntax, and hopefully also fix the bug regarding backticks inside embedded JavaScript.

Other features:

• Outputting ES2015 destructuring assignment is low-hanging fruit, along the lines of ES2015 computed properties. Anyone up for taking on a smaller task?

We’ve made tremendous progress. Great thanks to all those who have contributed so far, and if you’ve been watching from the sidelines, now’s your chance to be a part of CoffeeScript 2 😄

[coffeescriptbot]

From @greghuc on 2016-11-04 08:10

@GeoffreyBooth, regarding tagged template literals, I haven't made a start on this as I've had no time for open-source work in the last month. However, I should be able to make a start next Monday, and will update accordingly after that. Help from others is also appreciated.

My main priority is getting a crash course on the Coffeescript compiler. Useful links I know about:

• https://github.com/jashkenas/coffeescript/wiki/%5BHowto%5D-Hacking-on-the-CoffeeScript-Compiler
• https://github.com/jashkenas/coffeescript/wiki/%5BHowTo%5D-How-parsing-works
• https://github.com/jashkenas/coffeescript/wiki
• For testing: https://github.com/GeoffreyBooth/coffeescript-gulp
• Rise of the Transpilers talk by J Ashkenas

All, congrats on progress!

[coffeescriptbot]

From @connec on 2016-11-04 11:14

@GeoffreyBooth, I still think the approach outlined in #4330 (compile constructors to classes, leave everything else as-is) is the best approach for maximum backwards compatibility whilst still fixing extending ES2015 classes. This should make it a 'no-brainer' for v2, and we can make additional changes (e.g. super) down the line.

I plan to update the PR this weekend. Honestly I might just reset --hard 2 and work forward from there 😄

[coffeescriptbot]

From @GeoffreyBooth on 2016-11-04 15:36

@greghuc, others: I would be happy to host a webchat this weekend where I walk through what I understand about the CoffeeScript codebase. I certainly don’t understand all of it, really only the parts I touched in the PRs I implemented, but I’m happy to explain those as best I can. Would that help?

Both @greghuc and @connec, how would you feel about working in branches where multiple people can contribute? We can host them on your repos or mine; the owner would just need to add the various other contributors. I would be happy to help with either of your efforts.

[coffeescriptbot]

From @greghuc on 2016-11-04 18:46

@GeoffreyBooth a webchat would be great. Sunday would be best, as that gives me tomorrow Saturday to get my head round things.

Do you want to suggest a time + webchat-host that works?
I'm in the UK on GMT timezone.

I've just emailed you my contact details (used the email address on your geoffreybooth.com website).

[coffeescriptbot]

From @GeoffreyBooth on 2016-11-04 21:27

I can do Sunday, anyone else interested? I’m in California so it would probably be morning my time, evening UK time.

[coffeescriptbot]

From @mrmowgli on 2016-11-05 09:25

I got bogged down fairly early, and then got too busy to keep up. I have some more time coming up, and started going through the #4330 - are there any other threads I need to know about to help with the classes? I can also make sunday, depending on time. Also in California

[coffeescriptbot]

From @greghuc on 2016-11-05 22:13

@GeoffreyBooth I started work on tagged template literals, and opened a new WIP branch+pull request in your repo: #4352

[coffeescriptbot]

From @GeoffreyBooth on 2016-11-05 23:52

@greghuc that’s fine, thanks for starting a branch.

I have a few suggestions to help make getting PRs accepted go smoothly:

• If a branch isn’t ready for merging yet, but you want to open a PR for discussion, please put [WIP] at the start of the PR name. Not that we’re likely to merge it in accidentally anyway, but it can’t hurt.
• Features intended for CoffeeScript 2 should be submitted against the 2 branch. Only improvements that aren’t breaking changes should be submitted against master. I’ll keep 2 up-to-date with anything merged into master.
• Please don’t commit things you don’t intend to be merged. For example if you comment out a bunch of tests, please take care not to commit that change. Don’t commit console.logs, etc.
• Please follow idiomatic CoffeeScript whenever possible. So is, not ==, and so on. This is the CoffeeScript codebase, we should be setting a good example 😄

@mrmowgli the most current threads related to classes are coffeescript6/discuss#22 and #4330. Other useful ones are #4233 and decaffeinate/decaffeinate#397. @connec if you do end up going git reset for classes, can you please maybe start a new branch or a new PR? You wrote a lot of great inline notes in #4330, and I wouldn’t want those to get lost or hidden if you push a new branch into that PR. You could maybe just open a new PR for the new branch, and that way the notes in 4330 would be preserved.

@mrmowgli and anyone else who wants to join the video chat tomorrow, please send an email to my name at gmail. Thanks!

[coffeescriptbot]

From @GeoffreyBooth on 2016-11-06 18:56

More info on classes: https://github.com/coffeescript6/discuss/wiki/CS-classes-and-ES6-Classes-(WIP) and https://github.com/balupton/es6-javascript-class-interop

[coffeescriptbot]

From @GeoffreyBooth on 2016-11-07 00:21

BTW if anyone reading this is itching to get their first contribution into the CoffeeScript codebase, there’s a five-year-old PR that is sitting open just because it needs a little documentation: #1808

No coding required. Just write a good example.

[coffeescriptbot]

From @GeoffreyBooth on 2016-11-16 06:38

Update, 2016-11-16: Even since the beginning of the month, there’s been a lot of progress! The following PRs are almost ready to be merged; they just need a little more review before we feel confident that they’re up to snuff. Anyone have time to look them over and give notes?

• [CS2] Compile class constructors to ES2015 classes #4354: Classes! Or more specifically, outputting the class keyword, and support for ES2015 extends. This hopefully fixes our class interoperability issue, while leaving support for getters and setters and static for a future PR. Closes CS2 Discussion: Output: Classes coffeescript6/discuss#22 (with future issues for the remaining class features we decide to implement).
• CS1 tagged template literals (and CS2 interpolated strings as template literals) #4352: Tagged template literals! Written in such a way that it’s safe for the 1.x line. Closes CS2 Discussion: Features: Tagged template literals coffeescript6/discuss#28. Once that’s merged in, the work has already been done in this PR (see its comments) to output all interpolated strings using the ES syntax, so ES template literal syntax for the 2 branch will follow closely behind, which would close CS2 Discussion: Output: ES6 template literals for CoffeeScript interpolated strings coffeescript6/discuss#41.
• Triple backticks to allow creation of JavaScript blocks #4357: Triple-backtick operator for JavaScript blocks, and escaping backticks within JavaScript blocks. Closes CS2 Discussion: Features: Allow backticks to be used inside embedded Javascript blocks coffeescript6/discuss#42.

These aren’t done yet, but they’re close; please help get them over the finish line!

[coffeescriptbot]

From @danielbayley on 2016-11-26 15:26

Say I want to stick to functional programming; favouring composition over inheritance, avoiding classes and @/this as much as possible… am I right in thinking that CS2 [branch] is usable in place of ES6 as it stands right now?