CS2 Discussion: Question: Survey for devs/teams with maintained Coffescript codebases: happy with CS, or considering migrating?

[greghuc]

Coffeescript has been around since 2009. Since then, a lot of Coffeescript code has been written, and non-trivial projects developed with it.

Given we're discussing the future of Coffeescript, it would be great to get the views of developers/teams who have non-trivial, maintained CS codebases, which they plan to maintain and extend over the coming years.

Specifically, it would be good to know whether you/the team are:
a) happy to keep using Coffeescript for the project
b) are considering migrating the project from Coffeesript to ES6/other.

Here's a little markdown 'survey' template below to use, or feel free to comment free-style.

**CS project summary.**
Quick summary: n developers, lines of code, years established, etc

**Is the project considering a switch from Coffeescript to ES6/other?**
No, or yes with language being switched to.

**If considering switch from Coffeescript, please explain your reasons.**
Give your reasons.

**If not considering switch from Coffeescript (or are, but would ideally like to remain with CS), why are you happy with CS?**
Give your reasons.

[greghuc]

CS project summary.
1.5 developers, 14K LOC, 3 years established.

Is the project considering a switch from Coffeescript to ES6/other?
Yes, to ES6, but not immediately.

If considering switch from Coffeescript, please explain your reasons.
I'm uncertain over the long-term substainability of Coffeescript. As Javascript develops at rapid speed in both browsers and nodejs, I want confidence that Coffeescript will still interoperate with latest Javascript+libraries in 3-5+ years. Recent incompatibilities with ES6 have raised uncertainty for me (broken tagged literals, and reports of ES6 inoperability. So I might de-risk the project by switching to ES6 Javascript.

If not considering switch from Coffeescript (or are, but would ideally like to remain with CS), why are you happy with CS?
I feel more productive and less likely to make bugs with Coffeescript. It's a small, clean language with a functional feel. I don't consider ES6 massively superior to Coffeescript. Yes it's introduced some Coffeescript-influenced features, but it's also added even more complexity to Javascript.

[nwinter]

CS project summary.
Quick summary: CodeCombat, 7 core developers and hundreds of open source contributors, about 100K lines of code, 3.5 years old

Is the project considering a switch from Coffeescript to ES6/other?
Not actively considering, though a couple of us would like to. Maybe eventually. We'd go to ES6 or maybe Typescript.

If considering switch from Coffeescript, please explain your reasons.
It's a polarizing language that can make it harder to hire developers who think they won't like it. There's a perceived lack of momentum compared to ES6. There are a few cool things in ES6 we'd like to use. It's more future-proof.

If not considering switch from Coffeescript (or are, but would ideally like to remain with CS), why are you happy with CS?
Primarily the cleaner, more powerful syntax. There are some language features I can't live without. Also, no need to migrate our code. We haven't run into any interoperability problems yet.

[greghuc]

Re existing CS projects, @devongovett justifies porting fontkit from CoffeeScript to ES6 here. He also plans to migrate pdfkit to ES6.

[alangpierce]

CS project summary.
Benchling, 17 developers (about half of whom joined in the last 6 months), about 200K lines of CoffeeScript code, about 3-4 years old.

Is the project considering a switch from Coffeescript to ES6/other?
We've already decided to switch to JavaScript, and new code is written in JavaScript. I've been contributing a bunch to decaffeinate in my free time to make it easier to switch.

If considering switch from CoffeeScript, please explain your reasons.

• JS generally has better tooling, like linting, code coverage, etc.
• We were unhappy about various sharp edges in CoffeeScript, primarily implicit returns.
• We prefer JSX for React code, and we weren't comfortable with the risk and build complexity of CoffeeScript JSX solutions.
• We write fairly disciplined code and we're hoping to use flow at some point, which requires JavaScript.
• Once we decided to write new code in JS, moving off of CoffeeScript became important to reduce ramp-up cost for new people.

If not considering switch from Coffeescript (or are, but would ideally like to remain with CS), why are you happy with CS?

We're agreed on switching to JavaScript, but there are certainly some hesitations:

• Some people on the team still like CoffeeScript better, particularly range syntax and ?..
• Switching programming languages takes a lot of work and isn't particularly important for any company goals. By my super-rough estimates, converting the codebase to JS would take 4000 person-hours without decaffeinate and 400 person-hours with decaffeinate in its current form. That's a lot of time that could be spent building useful things that help people.

[greghuc]

Feedback from Atom Editor at atom/atom#12656. Relevant quotes:

• "the current strategy appears to be that when new files are checked into the codebase, those should be written in ES6. No more Coffeescript files should be added. Existing coffeescript files may be converted to ES6 when they undergo a major rewrite."
• "Only suggestion I'll make is that you swap the freakin' of and in operators the other way around so devs won't keep confusing the two when flipping between CoffeeScript and ES6."