afaik; all my current uses of clojure involves a single machine

I'\ve yet to run clojure on a cluster, though I won't rule out the possibility

is (async/chan) the same as (async/chan 0) or (async/chan infty) ? I used to think infty; but I'm now starting to think it's 0.

(chan 0) is not allowed, as there is an assertion that it must be a pos? number? @qqq

(chan nil) is equal to (chan)

Hi, I am getting this error when tring to use cider-find-var after connected to a remote server compiled using lein uberjar:

user-error: 'cider-find-var' requires the nREPL op "info".  Please, install (or update) cider-nrepl 0.15.0-SNAPSHOT and restart CIDER

(defn start-nrepl-server [port]
  (log/info "Start nREPL server at port:" port)
  (reset! g-nrepl-server (nreplsrv/start-server :port port)))

[cider/cider-nrepl "0.15.0-SNAPSHOT"]

[org.clojure/tools.nrepl "0.2.12"]

wait, are you using lein on the remote server or an uberjar?

because an uberjar won't have your plugins in it

I get that (swap! atom f) can execute f multiple times. Question: suppose we have multiple swap!'s -- is there any guarantee on the order in which the corresponding functions are claled?

the retry happens if another change to the atom happens between start and end of call to f

so if the first to start, is first to finish, it doesn't retry

other than that I don't think we can generalize much?

@noisesmith So I would add cider-nrepl into dependencies and have another try. Thanks!

f1 starts f2 starts f3 starts f1 finishes f2 -- oh fuck, cancelled f3 -- oh fuck , cancedlled -- do we have a guarntee that f2 will start/finish before f3 ?

cancelled? they run to completion, then run again

and no, it's based on the order they finish the first time

okay, I meant: f1 starts f2 starts f3 starts f1 finishes f2 / f3: completes, colmpare+swap fails do we have a guarantee that f2 will restart+finish before f3 ?

okay

no

if f2 takes longer than f3, it could retry more times

and finish last

okay, so if we have n running concurrently, it's: first to finish = finishes, updates atom second to finish = next to run

if the starts overlap, yeah

@cmal iirc the cider-nrepl github page has an example of adding it to an nrepl you start yourself - it's not automatic, you need to apply it's middleware to nrepl

Can anyone recommend readings on desgining systems with 'back pressure' ? I'm convinced core.async/back-pressure is right, ... but I clearly don't know how to correctly handle the backpressure.

trouble past 47933

clojure.core.async/put! has a limit of 1024 go blocks can be parked on one channel right?

why is there that this limit?

@oli : what is the problem? running out of memory? stack overflow? wrong answer? infinite loop ?

stack

not really a problem. just looking for improvement. ideally a lazy list of all primes.

🙂

sieve is notorious for memory consumption

what is your end goal? educational purposes? primality checking in the wild

?

just playing

i like the aesthetics of (cons var (function x)) and i'd like to find a way to preserve them

past trivial details like memory 😛

(defn swap-exactly-once! [my-atom my-func]
   (locking my-atom
    (swap! my-atom my-func)))

so I can then add something which implements the Atom interface, and now I have "one at a time swap!" atom

(disclaimer/apology, pasting from clojure irc) does anyone have any clues as to how i would maybe go about changing the behavior of the lein repl multline promt? it is not so hard to change the normal prompt in the :repl-options, but how to handle the multi-line case? right now if i type i get: (defn foo [] #_=> (println "this is foo")) but i want to edit what shows up where the "#_->" prompt currently is. (i want it just to be whitespace)

My macro-fu is weak 🙁. How do I turn this:

(eval `(potemkin/import-vars
        [clojure.spec.alpha
         ~@(clojure.core/keys (clojure.core/ns-publics 'clojure.spec.alpha))]))

(eval (let [ns (gensym)]
        `(let [~ns clojure.spec.alpha]
           (potemkin/import-vars
            [~ns
             ~@(clojure.core/keys (clojure.core/ns-publics ???))]))))

It's an unquoted context so you should be able to just use ns directly

instead of ???

Bit curious about the context though, how do you expect that to return a non-empty set of keys?

Using ns directly in ~@() fails. But this works:

(eval (let [ns 'clojure.spec.alpha]
        `(potemkin/import-vars
           [~ns
            ~@(clojure.core/keys (clojure.core/ns-publics ns))])))

it's because at the evaluation time of ~@() variable ns is bound to the value generated by gensym

Oh, right, I missed the intent of the let

So the problem here is the order of evaluation with regards to the two nested lets; you can't unquote-splice the ns-publics call because you need it to be evaluated in the context of the quoted let

something like this should work better:

(let [ns (gensym)]
  `(let [~ns clojure.spec.alpha]
     (potemkin/import-vars
       (apply vector ~ns (clojure.core/keys (clojure.core/ns-publics ~ns))))))

This way the call to (ns-publics G_00001) is generated by the quasiquote rather than evaluated outside it and spliced in, if that makes sense?

nice, it's more in spirit with the original idea 🙂

Disclaimer: sorry if it’s not the right channel to ask Looking for something like Lightbend Activator for Clojure: set of skeleton apps engaging popular frameworks and components, showcasing pattern. Maybe just a curated set of links? Thanks!

@dartov https://www.clojure-toolbox.com/ is pretty great

thanks pesterhazy! there is “Project Templates” category in the clojure toolbox, I’m looking for more like those templates

yeah the ones listed are great

also check tenzing (for boot frontend dev) and https://github.com/bhauman/figwheel-template for lein frontend dev

but of course all depends on what you actually need

@dartov Luke VanderHart gave a talk comparing ReactJS libs for ClojureScript https://www.youtube.com/watch?v=oRmj3IUkRVk with a companion repo showing the same app in 3 frameworks https://github.com/levand/qttt

Thanks Stuart, looks great

@dartov @stuartsierra note that that talk predates Rum, which is now my go-to framework (providing both Quiescent-style functional components and local state should the need arise)

hm, I should try rum; normally I’m a big fan of re-frame which seems to take a pretty different approach (re-frame definitely has opinions about where your state lives)

hi, how can I create a File type object from java.io.ByteArrayInputStream?