#clojure logs

2015-08-15

00:41mcktrtlis it possible to give an async channel a custom string representation somehow? so like, if I do something like (let [ch (chan)] (println ch)) I'll see something I can identify and not "clojure.core.async.impl.channels.ManyToManyChannel@25f32e46"
00:51oddcullymcktrtl: may with meta data?
00:51oddcully,(let [c (with-meta [] {:very :special})] (binding [*print-meta* true] (pr c)))
00:51clojurebot^{:very :special} []
00:55mcktrtl(with-meta (chan) {:very :special}) -> ClassCastException clojure.core.async.impl.channels.ManyToManyChannel cannot be cast to clojure.lang.IObj
00:55mcktrtlam i doing that wrong?
01:12amalloychannels don't support meta
01:12amalloy(is what that error message is saying)
01:18mcktrtlahh ok :( thanks
01:19rhg135I'd wrap it in a record/map
01:20mcktrtllike {:writer-ch (chan) :network-ch (chan)} ?
01:22rhg135Yeah
01:23rhg135Or a record and define a print-method
01:23mcktrtloh right, thanks. i guess i should have thought of that since i'm doing it already
01:24rhg135Np
01:24mcktrtli was just putting some logging in to a function that takes a channel as an argument and didn't think of the bigger picture
01:26rhg135It's unfortunate there is no metadata on channels
01:57amalloyrhg135: it's a little hard to imagine actually allowing it though, right? think of the consequences. (let [c (chan), c' (with-meta c {:blah true})] (go (>! c 1)) (go (<! c)) (go (<! c'))). which of the two reads returns 1? either? both?
01:58amalloywith-meta is supposed to return a value that's indistinguishable from the input, but you can't really do that because channels are mutable objects, not values
01:58amalloy,(with-meta (atom 0) {:blah true})
01:58clojurebot#error {\n :cause "clojure.lang.Atom cannot be cast to clojure.lang.IObj"\n :via\n [{:type java.lang.ClassCastException\n :message "clojure.lang.Atom cannot be cast to clojure.lang.IObj"\n :at [clojure.core$with_meta__4134 invokeStatic "core.clj" 217]}]\n :trace\n [[clojure.core$with_meta__4134 invokeStatic "core.clj" 217]\n [clojure.core$with_meta__4134 invoke "core.clj" -1]\n [sandbox$eval...
01:58amalloyit doesn't work for atoms or refs either, for the same reason
01:59amalloymetadata on channels is such an obvious thing there's no way rich *forgot* to do it; there's got to be a reason why it's no good. i speculate that it's this reason, but maybe it's some other one
02:09bacon1989so who else is hoping that clojure takes over the COBOL market?
02:10bacon1989I was thinking of writing an FFI for it, since I think it could probably adopt a lot of interested fellows
02:17TEttingerbacon1989: how would that work? I don't know if cobol usually runs on the JVM, but if it does then you probably wouldn't even need an FFI
02:26J_A_WorkTEttinger: there is a version of Visual COBOL that runs on the JVM apparently.
06:46devnWickedShell: (set *warn-on-reflection* true). My emacs setup shows me by underlining in yellow the places I'm missing hints. Cursive does something similar IIRC.
06:55expezdevn: which package does that underlining? squiggly-clojure?
08:52WickedShelldevn: right I'm familiar with that, however when I actually dump the heap very few of the instances caught by that are actually populating my 4 million instances of reflect (somewhere less then 1 percent). And I can't find enough in the object when looking at it in the heap dump to find it's origin
11:14joejagHello, I'm looking for help trying to figure out a simple way of solving a problem taking text from a collection until a condition is met: https://gist.github.com/joejag/5b19459f05a7cad977ff
11:54justin_smith,(reduce (fn [[s,n]e] (if (pos? n) [(str s (when (not-empty s) \,) e), (dec n)] (reduced s))) ["",2] (clojure.string/split "a,bb,ccc,dddd" #","))
11:54clojurebot"a,bb"
11:54justin_smiththat's a bit verbose, I guess
11:55justin_smith,(clojure.string/join \, (take 2 (clojure.string/split "a,b,ccc,dddd" #",")))
11:55clojurebot"a,b"
12:02gfrederickshello
12:02kwladykawhy the same code as jar file has better performance then in REPL?
12:02justin_smithbecause lein is slow
12:02justin_smithand so is nrepl
12:02gfrederickskwladyka: presumably "better performance" is just startup time?
12:02justin_smiththe biggest difference you will see is startup time
12:03justin_smithyeah
12:03kwladykajustin_smith, but i am counting time as (time ...) so startup time doesn't matter? does it?
12:04justin_smiththe other difference is that lein uses a jvm arg that turns off hotspot
12:04kwladykaeven more REPL started, load libraries and after then i run some command
12:04justin_smithand usually with an uberjar you won't be turning that off, and for some code bases that can make a big difference
12:06kwladykajustin_smith, if i run java with -Xint can i check if it is that?
12:08justin_smithkwladyka: yeah, that should test it
12:10kwladykaanyway i am writing article about how to improve algorithm performance. If you can share with me any interesting article which i can read to make something better will be great :)
12:14kwladykajustin_smith, hmm i don't think it is because hotspot
12:14kwladykawithout hotspot it takes agaes, much much worst then REPL
12:15justin_smithkwladyka: lein turns off hotspot
12:15justin_smiththis is a documented fact
12:15kwladykajustin_smith, i understand but when i runed jar without hotspot it takes ages.... i couldn't even wait to finish counting
12:15kwladykahmm
12:15kwladykavery strange
12:16kwladykabased on that fact extremely strange :)
12:17justin_smithkwladyka: you can use :jvm-opts ^:replace ["-server"] to see how lein repl performs with hotspot on
12:17justin_smith(that's a config you add to project.clj of course)
12:18kwladykajustin_smith, is it equal :jvm-opts ["-Xms4g" "-Xmx4g" "-server"]) ?
12:18justin_smithno, your "-server" arg does nothing because you are not using the ^:replace metadata
12:18kwladykaok
12:19justin_smithso keep those opts, and throw in ^:replace as a metadta
12:19justin_smithkwladyka: the reason is that jvm opts are merged with the lein defaults, and those override the -server options, but ^:replace prevents that
12:21kwladykayou know so much about Clojure, are you close to develop clojure.core?
12:21justin_smithkwladyka: I haven't really tried
12:21justin_smithI'm too lazy
12:22kwladykabut you looks like a guy with huge experience about Clojure :)
12:22justin_smithyeah, I'm barely (and not really) meeting my deadlines at work though, and clojure.core doesn't even pay money
12:24kwladykajustin_smith, running with :jvm-opts ^:replace ["-server" "-Xms4g" "-Xmx4g"] didn't change the time
12:24kwladykamaybe it has even few seconds more
12:25kwladykajustin_smith, can i ask you what kind of software are you creating?
12:25kwladykajustin_smith, yes with -server it is running even longer about few seconds
12:25justin_smithkwladyka: a paid app for social media discovery
12:25timothywQuick question
12:26timothywI want to print out a long list - but Clojure ellides some of it
12:26timothywhow can I print an entire list to string / edn
12:26timothyw… already tried pr , pr-str , etc
12:27justin_smith,*print-length*
12:27clojurebot5
12:27justin_smiththat value effects all of those printing methods
12:27justin_smithif it's set to nil, there will be no limit
12:27kwladykatimothyw, and i suggest use pprint <- it is much more readable
12:27timothywa ha
12:27justin_smith,(doc clojure.core/*print-length*)
12:27clojurebot"; *print-length* controls how many items of each collection the printer will print. If it is bound to logical false, there is no limit. Otherwise, it must be bound to an integer indicating the maximum number of items of each collection to print. If a collection contains more items, the printer will print items up to the limit followed by '...' to represent the remaining items. The root binding is...
12:28timothywkwladyka: yeah I definitely tried that
12:28justin_smithtimothyw: you can change the value with set! https://clojuredocs.org/clojure.core/*print-length*
12:29kwladykajustin_smith, are you coding only in Clojure or you are polyglot?
12:29justin_smithkwladyka: the app is 100% clojure unless you count like sql
12:30kwladykajustin_smith, nice
12:30timothywwhew - awesome that does the trick
12:30timothywcheers
12:31kwladykajustin_smith, BTW: do you have any idea why REPL is slower then jar? my tests didn't prove it is because hotspot. Even more when i runed jar with -Xint it takes much much longer then REPL.
12:32justin_smithno, I don't know what the other difference would be
12:32kwladykaok
12:32kwladykaanyway it is strange REPL works faster then jar without hotspot...
12:33kwladykacan i check if hotspot is runed in REPL?
12:33justin_smithkwladyka: one difference, maybe is that lein does not turn on Xint, it uses the TieredCompilation=0 or something like that
12:33justin_smithkwladyka: iirc there is a vm flag that will make any runtime optimization decisions verbose...
12:34kwladykajustin_smith, but nothing really appear on screen, but maybe it can affect the time
12:35justin_smith-XX:-PrintCompilation maybe
12:36justin_smithhttp://www.oracle.com/technetwork/java/javase/tech/vmoptions-jsp-140102.html
12:39kwladykajustin_smith, i runed with this flag jar file and it doesn't change anything
15:10sdegutis(remove nil?) is usually what you actually want as opposed to (keep)
15:12justin_smithsdegutis: unless the alternative is (remove nil? (map ...)) because you should just use keep in that case
15:14sdegutisjustin_smith: false goes away in that case too
15:14sdegutissometimes you want to keep true/false but remove nil
15:15sdegutisLike how booleans have three choices (true, false, file not found).
15:15justin_smith,(keep identity [false true nil 1])
15:15clojurebot(false true 1)
15:18sdegutisOh right, I misremembered (doc keep). It only does nil.
15:18sdegutis(keep identity) == (remove nil?)
15:19sdegutisBut (remove nil?) expresses intent much more clearly though.
15:19justin_smithsdegutis: what else would keep mean other than "I don't want the nil results from this mapping"
15:20sdegutis"keep" isn't the problem, "identity" is.
15:20sdegutisremove nil? is much more English, keep identity is much more C++
15:20justin_smithI mean I don't use (map identity ...) either
15:21sdegutiskeep identity makes use of more implications, remove nil? is completely straight forward
15:38gfredericks,(doc keep)
15:38clojurebot"([f] [f coll]); Returns a lazy sequence of the non-nil results of (f item). Note, this means false return values will be included. f must be free of side-effects. Returns a transducer when no collection is provided."
15:38gfrederickshaha transducer
15:39justin_smithgfredericks: combines map with (partial remove nil?), very useful
15:40gfredericksyeah I've used it before; was just curious if it got transducified
15:40sdegutisQuestion: are transducers effectively the same as partial'ing semantically (aside from their better performance)?
15:41sdegutisSo is (partial remove even?) the same as (remove even?)?
15:42gfredericksnope
15:42gfredericksthey're a moderate haskellian headache
15:42sdegutisHow are they different? It seems like you could use them the same way.
15:42sdegutisOh?
15:43gfredericks(map foo) is a transducer, and a transducer is a function that transforms reducing functions
15:44sdegutisWould you use them similarly to how you would with ->> just without the ->> ?
15:45gfredericksyou can combine them with comp
15:45sdegutisI really don't understand transducers, I read the docs and I just don't fully get it.
15:45gfredericks,(->> (range) (map inc) (filter even?) (take 5))
15:45clojurebot(2 4 6 8 10)
15:45Bronsasdegutis: transducers have nothing to do with currying
15:45sdegutisSo instead of (->> (range) (remove even?) (take 3)) you would use ((comp (remove even?) (take 3)) (range))
15:45gfredericks(reduce ((comp (map inc) (filter even?) (take 5)) conj) [] (range))
15:45gfredericks,(reduce ((comp (map inc) (filter even?) (take 5)) conj) [] (range))
15:45clojurebot[2 4 6 8 10]
15:46sdegutis##(->> (range) (remove even?) (take 3))
15:46lazybot⇒ (1 3 5)
15:46gfredericks^ I had no idea if that would work or not
15:46sdegutis##((comp (remove even?) (take 3)) (range))
15:46lazybot⇒ #<core$filter$fn__4361$fn__4362 clojure.core$filter$fn__4361$fn__4362@3e7b8ad4>
15:46sdegutisAh.
15:46gfredericksnote how I made the transducer and then called it with conj as its arg
15:46sdegutisAhh.
15:47gfredericksconj being the reducing function
15:47BronsaOTOH you shoulnd't use them that way
15:47gfredericks:)
15:47Bronsatransduce makes it easier
15:47sdegutisHow?
15:47gfredericksyeah there's like three new functions for executing that stuff?
15:47justin_smiththe major difference with transducers is that you don't make a shitload of lazy-seqs that aren't actually useful
15:47gfredericks~the major difference with transducers is that you don't make a shitload of lazy-seqs that aren't actually useful
15:47clojurebotRoger.
15:48justin_smith,(sequence (comp (map inc) (filter even?) (take 5)) (range))
15:48clojurebot(2 4 6 8 10)
15:48Bronsa(reduce ((comp (map inc) (filter even?) (take 5)) conj) [] (range)) is (transduce (comp (map inc) (filter even?) (take 5)) conj [] (range))
15:48sdegutisjustin_smith: so it's simply/merely/only a performance boost?
15:48sdegutisand serves no other purpos?
15:48Bronsano
15:48justin_smithsdegutis: that's not the only purpose no
15:48Bronsasdegutis: read the transducers page in clojure.org
15:49justin_smithit also makes it easier to implement the core functions like map, filter, etc. for new data sources (eg. channels in core.async)
15:49justin_smith(inc Bronsa)
15:49lazybot⇒ 118
15:49justin_smithyeah, that's the right answer
15:49justin_smithhttp://clojure.org/transducers
15:50sdegutisBronsa: I'll read it again but last time I read that it seemed like useless marketing rhetoric
15:51Bronsasdegutis: you must have read a different page than the one I've read then
15:51justin_smithsdegutis: can you point out which part of clojure.org/transducers is marketing?
15:51sdegutisjustin_smith: must be mixing it up with another page
16:04justin_smith,(into [] (comp (map inc) (filter even?) (take 5)) (range)) ; equivalent to Bronsa's transduce
16:04clojurebot[2 4 6 8 10]
16:34expezIf some user does (def foo 1) at the repl. Is there some way to reset this, without knowing the names of the created vars?
16:35expezhttps://github.com/clojure-emacs/cider/issues/1240 I think this user has a pretty weird workflow, but if there's an easy fix to recommend that would be nice.
16:35justin_smithexpez: you could delete the user namespace. You could use ns-publics or ns-interns to see what all is defined.
16:36justin_smithexpez: and yeah, like mentioned in that thread, tools.namespace is designed to do that kind of full ns reset
16:36expezjustin_smith: delete and recreate the namespace? That seems like the simplest thing that could possibly work.
16:36amalloyremove-ns is the easy answer, but then you lose the ns mappings to vars in other namespaces
16:37amalloy,(doc ns-interns)
16:37clojurebot"([ns]); Returns a map of the intern mappings for the namespace."
16:37expezjustin_smith: tools.namespace is limited to undef vars existing in the project, though, right? Anything created at the repl won't be affected?
16:37amalloy,(ns-interns *ns*)
16:37justin_smithexpez: it restarts namespaces from scratch, removing definitions that are not reflected in the source
16:37clojurebot{}
16:37amalloy,(def foo 1)
16:37clojurebot#'sandbox/foo
16:37amalloy,(ns-interns *ns*)
16:37clojurebot{foo #'sandbox/foo}
16:37expezThe user reports trying cider-refresh, which calls out to tools.namespace :/
16:38justin_smithoh, OK. So yeah, either using ns-interns and selectively ns-unmap to delete bindings, or destroy and recreate the ns
16:39expezCan you think of any reason to prefer one over the other? Seems like an easy feature to implement, though I'm not sure it'll get widely used heh
16:40justin_smithexpez: seems like it wouldn't be hard to implement a function that would take out all definitions and bindings from a namespace, and then use refer-clojure to get the defaults back
16:41expezindeed, thanks guys!
16:41expez(do (inc amalloy) (inc justin_smith))
16:42expezsuppose that was too much to ask for, clojurebot :)
16:42amalloyjustin_smith: if you use ns-interns you won't lose the defaults
16:42justin_smithamalloy: but then you also wouldn't unmap required namespaces right?
16:43justin_smithexpez: lazybot is not nearly so clever, inc is a pseudo-syntax
16:43amalloywas that a requirement?
16:43justin_smithperhaps only in my imagination :)
16:43amalloyin mine it was a requirement to leave them alone
16:44justin_smitha full tools.namespace refresh would get rid of any require that wasn't reflected in the ns definition on disk iirc
17:12bielllsHi, I've been following the clojurescript tutorial on OS X and I can't get this section (https://github.com/clojure/clojurescript/wiki/Quick-Start#less-boilerplate) to work properly
17:13bielllsI have changed build.clj and index.html as indicated, but i get Uncaught ReferenceError: goog is not defined(anonymous function) @ main.js:1
17:44arkhbiellis: would you be able to upload what you have so far somewhere?
17:46bielllsSure, I will post it on github in a sec
17:53bielllsarkh: Nevermind, I just realized that it was because i had initially added build.clj in src, and my emacs buffer was still saving my edits there even though I had moved the file. Thanks for your help anyways
17:54arkhbiellls: cool
18:38dfcarpenterakHi everyone, I’m an intermediate javascript developer who made my way to Clojure (also been playing with Elixir as well) through looking into solutions for concurrency/scalability problems with nodejs. Also, I’ve also been using React js + immutable js on the front end and been really enjoying that as well. Anyways, as I slowly become more familiar with Clojure I was wondering if anyone could point me to what are
18:38dfcarpenterak considered well designed web-focused open source clojure apps. I’m looking for apps + any reading materials through which I can glean good general architectural recommendations for scalable concurrent clojure apps.
18:54TEttingerdfcarpenterak: hm, good question. I don't write web apps, but I think the closest you'll find to an open source _complete_ web app is libraries that have been open sourced from a closed-source commercial venture. I suspect there's not enough motivation to open source a large app and allow a competitor access to your app's internals... there's likely some good architecture advice on dev blogs though.
18:55TEttingerOm is likely something you want to look into, it's ReactJS-based
18:55TEttingeror was it Rx
18:56dfcarpenterakYeah, I have been playing around with Reagent + reframe also
18:56TEttingerI can't keep track of all this stuff I don't use :)
18:56dfcarpenterakhttps://github.com/Day8/re-frame
19:35domokatowhy is there no dissoc-in?
20:04gfredericksI think because there aren't obvious semantics for such a function
20:05gfredericksbut I might be confusing it with something else
20:06justin_smithwhat should (dissoc-in {} [:a :b] :c) return?
20:09gfredericksI imagine the call would just be (dissoc-in {} [:a :b])
20:10justin_smithoh, right, of course
20:10justin_smithI still don't know what it would return
20:19gfrederickseither {} or nil
20:19gfredericksapparently there is such a function in core.incubator wherever that is, so we could go look at it
20:21justin_smithhttps://github.com/clojure/core.incubator/blob/master/src/main/clojure/clojure/core/incubator.clj#L62
20:25justin_smithhttps://www.refheap.com/108261
20:26AWizzArdMaybe something like (update-in m [k1 k2 k3] dissoc :key)
20:26justin_smithAWizzArd: on my refheap paste you can see what the version from incubator does
20:42hiredmanI have this kademlia implementation I am playing with, and it stores some information as a vectors, but that information could just be stored as ByteBuffers, but when I make that change it causes a stackflow where all the frames are at clojure.lang.PersistentHashMap$BitmapIndexedNode.assoc(PersistentHashMap.java:693)
20:43hiredman:/
20:53Bronsahiredman: how does PHM come into play?
21:07hiredmanthe vectors/bytebuffers are stored in a set in a map
21:08hiredmanwhich is stored in a record, in a map, in a atom
21:08hiredmanso I am not even sure which map level is the one that starts stacking
21:17hiredmanah, it must be related to bytebuffer's crazy .hashCode calculation, it changes depending on how many bytes are remaining
21:19amalloysounds right to me. using anything mutable as a map key goes wrong pretty fast
21:20hiredmanyeah, but I often have something is just a chunk of bytes, which is a perfectly fine value, the jvm just doesn't have a great type for it
21:21hiredmanbytebuffers are almost not terrible, they have value equality and hashing, but the value is dependent on all the mark and position stuff
21:21hiredmanStrings are immutable, but double the storage space and cause lots of copying
22:00gfredericksdouble the storage space?
22:00justin_smithgfredericks: bytes stored as utf16 is my guess
22:00justin_smithjust a guess though
22:01gfredericksjust to make charAt fast?