Am I the only one amazed by what the Clojure community and core team are conjuring up?
Doing client-side programming with things like CLJS, Figwheel, Reagent and core.async feels miles ahead of what we have in moden-js-land (es6/7, babel, webpack, React, promises).
If you were to start a startup today, would you be comfortable going with something like Clojure/script?
Everything you've mentioned has been awesome for us. The arrows we take as pioneers are things like having to roll libraries for email-as-a-service, stripe, etc. Granted it's usually easy but can be time consuming.
The Clojurescript community are ahead but not by that much. To list specifics, cljs->babel+and immutable lib, figwheel->react-hot-loader, reagent->react 0.14 pure components, core.async->js-csp (or async/await).
In terms of non-component organization, I believe re-frame is a significant improvement over redux. Reactions are good when you don't control the endpoints, splitting out the reducers into pure functions is good, but adding middleware on them is the real win. On the other hand, it wouldn't be that hard to adapt the model to redux.
The next phase of organization is integrating Relay/Falcor concepts. David Nolan gave a talk about this in Om Next at NYC Clojure last month and there is a video. Om Next as presented is very compelling if you're on Datomic and less so otherwise.
As to your startup question:
I've been a full time cljs dev on a b2b app at Reuters for the past 9 months. I took up the job specifically because I wanted to write cljs. I had been involved with the Clojure community (I care about state) but only working on toy projects for the previous ~4 years.
My experience with Clojurescript is that it was less of an improvement on modern js than I was expecting. The biggest advantages are protocols and the standard library being both rich and standard. Nice to haves but non-critical are native syntax for immutable maps and multimethods. I guesstimate I write ~10% less code in cljs versus js but you're ultimately writing the same stuff.
Problems I've run into:
Full build time for this app is long. Our app is in the 15k LoC range across ~150 files and cold compile is 140s on a 2012 MBA. It's annoying but incremental compilation times are sub-second after some build config tweaking.
We have one component in particular that tends to get lost when switching branches and the missing namespace forces a fresh compile. Our cljs version is from June so this may be fixed. I've also spent a number of hours debugging problems that turned out to be stale build issues.
I tried a couple times unsuccessfully to get Emacs (cider) to connect to a figwheel repl. After a few evals things simply become unresponsive. Just using figwheel is good enough but I miss the in-editor repl. Haven't tracked down the reason, could be my lack of emacs knowledge.
If you're using core.async, the main loop has a try/catch/rethrow. This causes Chrome Dev Tools to break in the outer loop instead of actually at the problem. You have to explicitly err.stack in the console (which is not source mapped) and don't have access to the locals unless you manually set a breakpoint at the error and reload. You also get to learn to read the JS representation of Clojure literals. None of this is impossible and if you're working in a tight loop you tend to have a pretty good idea of what the error is without jumping through debugger hoops but if you're doing something like switching branches or refactoring it's annoying.
I like Reagent but I've had a number of times where its behavior doesn't match my expectations. In particular, figuring out what part of the vdom is invalidated on a ratom change caused me problems. There's a gotcha that sequences must be forced with doall or you'll get weird behavior. At the moment I have a very expensive reaction (list processing ~6k items) that's getting run 8 times in response to a single key change in the source ratom so I'll be tracking that down tomorrow.
I don't consider this list a reason to not adopt Clojurescript. I can make a similar list for the Babel stack.
As for the question of would I be comfortable, I like writing clojurescript but I'd only really recommend it if you're committed to full stack Clojure. It takes a number of weeks for a new frontend hire to ramp up on the language. I've discussed this with the other frontend specialist on the team and our consensus is that cljs is a better language but we're not that much more productive in the language compared to ES2015 so I'm not really convinced the weeks of ramp up time are worth it. Our experience with hiring has been that we've had very few candidates but they've all been skilled.
The Clojurescript community are ahead but not by that much. To list specifics, cljs->babel+and immutable lib, figwheel->react-hot-loader, reagent->react 0.14 pure components, core.async->js-csp (or async/await).
Immutable, js-csp, etc... were all inspired by Clojurescript, I guess that's the point the grandparent was trying to make.
> If you're using core.async, the main loop has a try/catch/rethrow. This causes Chrome Dev Tools to break in the outer loop instead of actually at the problem.
OMG! Is that what is causing that behaviour?! It's frustrating (though not a show stopper) and I was unsure of the cause. Thanks for pointing that out. I will have a deeper look.
Doing client-side programming with things like CLJS, Figwheel, Reagent and core.async feels miles ahead of what we have in moden-js-land (es6/7, babel, webpack, React, promises).
If you were to start a startup today, would you be comfortable going with something like Clojure/script?