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hi everybody, can anyone recommend a free video tutorial on how to build webapps with clojure?
looking for some general advice on getting started. I want to build a websocket backend in clojure. I've read up on the basics of clojure, and I've made it through the first few chapters of living clojure. Would it be more advantageous to finish the book and learn the more advanced topics before I start the app, or should I learn as I go?
when I was learning python/django a few years ago, it was pretty easy to pick things up as I came across various problems. But something tells me clojure's more advanced topics might make that tough
bcoop713: Jump right in You could also check out @magnars excellent game tutorial, http://www.parens-of-the-dead.com .. It features a frontend and backend communicating using websockets.
thanks, just bookmarked it actually. Does that tutorial use the core.asyc library at all?
Clojure is hard only if you are not familiar enough with functional programming IMO. Most of it's features are straightforward to understand. It might get a bit harder when trying to understand how to write applications with component or how to use core.async effectively, but for the most part the language is straightforward.
python has fast startup, so not everybody cares to work from/on a repl, the jvm/clojure on the other hand....
I don't think I saw a single example of using the python repl for debugging. Only time it came up was in the first chapter of a python tutorial haha
in scheme, for example its so fast, you don’t need to adopt that typical lisp-like workflow
Interesting, I'd think it would be more similar to Ruby - I was debugging using pry all the time, which is basically an interactive REPL.
Even though I agree it's not really all that needed, but I kinda got exposed to Haskell early on through ghci.
well once you're used to working like this it's painful to work without, it's not uncommon to have a single repl session running all day without a restart.
@tmtwd: but I'll give you that the JVM makes some things more difficult. I basically hate Java so when I had to deploy Clojure and had to deal with them JARs, WARs, servlet containers and what have you - that was painful. Also the parts where Clojure internals stick out or you have long-winded stacktraces and bad error messages.
I found ClojureScript a lot easier to get started with than Clojure, just because of the Java environment stuff.
I think it depends on what you are familiar with. I found Clojure easier to start with because I’m familiar with the jvm.
I've always enjoyed using a repl; even with python, startup time wasn't so small that putting in several print statements was faster than loading a repl and blocking at the part I needed to debug
@roberto: Yeah, totally based on familiarity - there's a lot of web development stuff that is a bit of a nightmare to figure out if you've never done it before
I also find deploying jars easier than deploying a python app. I had so many issues deploying python and rails apps.
Oh, JVM is a solid piece for engineering, that's for sure. It also fives you an ecosystem of battle-tested libraries. But I just can't stop doing "UGH JAVA" each time something non-Clojure sticks out : V
being able to inspect the program state at the precise point where I'm having difficulty -- without having to restart the program -- has been an immense boon
tmtwd: depends on the language, but generally mark the line of code near where I'm having trouble so the debugging stops there
@roberto: re: deployment that's certainly true. Being able to pack up (almost) everything in an uberjar and just run it? That's certainly nicer than the dependency hell Python or Ruby have. But it's kind of assumed to be common knowledge in the Clojure land, which it exactly isn't if you don't come from Java.
well the I never touched the whole war/servlet containers thing, I just uberjar all the things and handle the static stuff separately in deploys. less headaches
tmtwd: I'm not entirely certain, tbh, since my functions are generally really small, I just iterate through definitions until I get it right
I've heard cider+emacs has the ability to place break points, but I haven't experimented with it yet
Weighing in on the whole JVM thing, The JVM is a plus if you’re already invested in Java and it’s ecosystem. If you’re coming from Python/Ruby/Erlang/etc, and you don’t already have that investment in the JVM then it can be a real downer.
tmtwd: but there again I'm using the repl to do so; so different kind of use, similar benefit
eh, the ecosystem is overstated. sure there’s a lot of java libraries out there, but frankly a lot of it is crap. And there isn’t really any killer library that doesn’t exist in other ecosystems. So I don’t really see it as a huge plus.
just on top of my head, it's probably the most polished networking lib out there, all languages/platforms considered
I mean, what do I want really, database drivers, web/networking stuff? all of those are covered just fine in other languages too. Aside from that I can’t think of anything in Java-land that I’d actually want.
plus, i think it becomes a negative when the internals of the wrapped java libraries jump out and bite you. then you’re back in imperrative-mutable-state-java-land again
Well, that's hardly unique. Maybe the quality of implementation is, can't compare that though.
But for some indie-ish explorations? It could be cool. Especially if you could model the world with Clojure STM.
still, none of this screams “OH MY GOD JVM IS AWESOME” to me, it’s a selection of mediocre libraries with correspondingly mediocre equivalents in other languages. I just don’t see the big draw, because I’m not already invested in the JVM. Now for the guys who have 15 years of production java to work with, and enterprise things to consider, I can see that being a boon. But that’s not me, and I suspect I’m not alone in that position in this community
Python can probably rival that, since it's a go-to language for scientists, but I don't think much else can.
Yeah, sorry, I'm trying to understand core.async so my questions aren't that well informed atm
I'm reading through a couple tutorials, but I'm still a little too ignorant to know what to ask
I don’t understand transducers, and have not had any need for it. And that is ok. Similarly, if you don’t find a need for core.async yet, that is fine. You don’t have to grok everything and pile it in your code just because it exists.
Yeah, I suppose at first it might not be so obvious what to ask about. But in general how I structure core.async code isn't all that much different from how I structure normal code (at least not enough that I would have an obvious answer for you). It's a bit of a feature of core.async - that you can write your async code similarly to the sync code. Though I didn't yet have to write tons of core.async, just some, so maybe it's different down the line.
I’ve only used it when doing network requests. It isn’t a prominent thing in my apps.
when I was writing a frp node backend, i broke my code out into inputs, transformers, and outputs
look at the workshop given by david nolen in the cognitec website if you want to see some more intermediate to advanced usage.
On the JVM stuff, are there many products that only really have Java APIs and there aren't any other real options? I know of a couple instances like that in .NET where in the past your only real option was the .NET API or C++
again, I think java has the best game libraries outside of c++, but at this rate, probably won't be long before rust is a rival in that space
@bcoop713: Do you know of any really good ones off the top of your head? I've never really looked into that space for Java
@shaun-mahood: I did once work at a job where we needed to interface with some ancient and horrifying database system, which only had decent drivers in java. We ended up wrapping it in python. That’s the only case I can think of, but I’m sure the enterprise world is full of similar stories.
Eh, but while the usual "Java is slow" spiel means little for webdevelopment, this is actually significant in game development unfortunately. So there's that to take into account.
there is also Adobe Experience Manager, which is unfortunately taking the enterprise CMS world by storm
I'm kind of new to the concept of logging as opposed to just println'ing everywhere. Is it normal to put log statements everywhere in a codebase? I keep debuggins something, logging a bunch of stuff to figure it out, then leaving it there. Is it fine to pull in the logging stuff in pretty much every namespace and just logging stuff all willy nilly or should I be trying to be more discretionary?
@jjttjj as roberto alluded, you can have your cake and eat it too by using debug-level logs. you can just leave them in or take them out as you prefer, and you'll only ever see them if your log level is set to debug or below
@dave so it's not really bad coding style per se to have a bunch of logging statements littered throughout all the namespaces, so long as they are potentially useful, ie they were added during debugging something then just left in?
i generally like to keep things tidy, so if i put in a debug log statement that i don't think i'll ever need to see again, i'll remove it when i'm done debugging
you can see some examples here: https://github.com/alda-lang/alda/blob/4d29d7556ac2e238330542ef6f9b44fee1eb688e/server/src/alda/sound/midi.clj
being able to see when MIDI events happen is a useful thing when i'm debugging, so i keep those debug statements in