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clojurians | clojure | ah, it should be `~@(for` instead of `~(for` | 2017-12-17T21:15:38.000064 | Berry |
clojurians | clojure | <https://pragprog.com/book/shcloj3/programming-clojure-third-edition> | 2017-12-18T00:07:12.000033 | Daniell |
clojurians | clojure | Did you guys checked <https://github.com/EntilZha/PyFunctional> ? I'm wondering if I could create a similar project with clojurescript. | 2017-12-18T02:11:45.000263 | Jami |
clojurians | clojure | Hi, I use
```
(defn gen-handler
[k]
(eval
`(defn ^::blocking ~(symbol (str (name k) "-handler"))
[state#]
(try
(handlers/do-handler state#)
initial-state
(finally (run *agent*))))))
```
to define function at runtime, but it appears the new `xxx-handler` function was defined at `clojure.core` namespace, not the namespace which `gen-handler` was called or defined. How to define a function at runtime at the current namespace? Thanks! | 2017-12-18T02:45:23.000254 | Tari |
clojurians | clojure | ```
(def □ 20 )
□
(comment
20)
```
so it clearly works
however, according to <https://clojure.org/reference/reader#_symbols> is this guaranteed to work? in particular, it states:
```
Symbols begin with a non-numeric character and can contain alphanumeric characters and *, +, !, -, _, ', and ? (other characters may be allowed eventually).
```
and I do not know how unicode is defined wrt to alphanumeric | 2017-12-18T02:49:56.000186 | Berry |
clojurians | clojure | <@Tari> have you considered using macro that this use case ? | 2017-12-18T03:19:42.000108 | Jami |
clojurians | clojure | <@Jami> I am not sure, does macro different with function in this use case? | 2017-12-18T03:20:30.000079 | Tari |
clojurians | clojure | at every thread the `agent` runs in, I use `(gen-handler k)` to generate a handler to do a specific job. | 2017-12-18T03:22:02.000317 | Tari |
clojurians | clojure | this handler is generated using the keyword `k` so I can later using keyword `k` to get the function's name and call this function. | 2017-12-18T03:23:21.000188 | Tari |
clojurians | clojure | do you have a specific reason to define top-level function with defn ? It might be more appropriate to create anonymous function with lambda | 2017-12-18T03:24:24.000410 | Jami |
clojurians | clojure | like in this case, where I define two handler functions
```
(defn pipe "Create a parallel pipeline."
[xf in out err]
(let [n ncpu
close? true
to (async/chan n)
from (-> in line-seq async/to-chan)
ln-handler (fn [x] (writeln out x))
ex-handler (fn [x] (writeln err x))]
(async/go-loop []
(when-let [ln (async/<! to)] (ln-handler ln) (recur)))
(async/pipeline-blocking n to xf from close? ex-handler)))
``` | 2017-12-18T03:24:45.000188 | Jami |
clojurians | clojure | <@Berry> Not sure what you mean by "is it guaranteed to work"? Do you mean, will it ever change in a future version of Clojure? It is unlikely that it will change, as the Clojure core team likes to maintain backwards compatibility, but I don't think they or anyone else can make you some kind of binding promise about it. | 2017-12-18T04:11:35.000062 | Micha |
clojurians | clojure | I believe the Eclipse Public License is pretty much a guarantee that you can use all versions of Clojure released under that as long as you want to, but that may not be what you are asking about. | 2017-12-18T04:19:08.000232 | Micha |
clojurians | clojure | <@Micha>: re "unicode in clojure", my current understanding is:
1. unicode var names works in 1.9.0
2. unicode var names is NOT promised to work according to clojure docs
3. I'm curious whether I can rely on unicode var names working in the future | 2017-12-18T06:41:33.000179 | Berry |
clojurians | clojure | :water_buffalo: | 2017-12-18T07:46:50.000166 | Sanford |
clojurians | clojure | :water_buffalo: | 2017-12-18T07:49:07.000159 | Sanford |
clojurians | clojure | Is there a way in `Pedestal` to automatically reject http requests that is not accepted by the application depending on `Content-type´? I tried the above code but I think I didn’t undestand what pedestal does
```(ns job-queue.service
(:require [io.pedestal.http :as http]
[io.pedestal.http.route.definition :refer [defroutes]]
[io.pedestal.http.body-params :as body-params]
[ring.util.response :as ring-resp]
[io.pedestal.http.content-negotiation :as conneg]
[io.pedestal.http.route :as route]
[job-queue.api.agent-api :refer [add-agent]]
[job-queue.api.job-api :refer [get-jobs]]))
(def supported-types ["application/json"])
(def content-neg-intc (conneg/negotiate-content supported-types))
(defn home-page
[request]
(ring-resp/response {:message "pong"}))
(defroutes routes
[[["/" {:get home-page}
^:interceptors [(body-params/body-params) http/json-body]
;;agent api
["/v1/agents" ^:interceptors [content-neg-intc] {:post add-agent}]
(def service {:env :prod
::http/routes routes
::http/resource-path "/public"
::http/type :jetty
::http/port 8080
::http/container-options {:h2c? true
:h2? false
:ssl? false}})
``` | 2017-12-18T08:01:04.000280 | Audie |
clojurians | clojure | and my `add-agent` always return `HTTP 200``
```(defn get-jobs
[r]
{:status 200
:headers {"content-type" "application/json;charset=utf-8"}})``` | 2017-12-18T08:02:26.000283 | Audie |
clojurians | clojure | When I send a request with `Content-type` `text/html` the response is `HTTP 200` too | 2017-12-18T08:03:34.000108 | Audie |
clojurians | clojure | Anyone know of any library wrapping an external queue (rabbitmq, Kafka, etc) as clojure.async channels? | 2017-12-18T11:12:37.000797 | Twanna |
clojurians | clojure | <@Twanna> I’ve done it several times, but getting the semantics right can be tricky | 2017-12-18T11:30:10.000939 | Sandy |
clojurians | clojure | Esp once alt! gets involved | 2017-12-18T11:30:33.000504 | Sandy |
clojurians | clojure | Be wary of claiming to have processed a message that you have merely dumped into a channel | 2017-12-18T11:30:47.000056 | Hugo |
clojurians | clojure | Kafka is probably the easiest since it’s immutable | 2017-12-18T11:31:58.000028 | Sandy |
clojurians | clojure | <@Sandy> any open source library that already does it or did you implement it yourself? | 2017-12-18T11:36:53.000061 | Twanna |
clojurians | clojure | <@Twanna> funny just opened the slack now as i was just doing some coding on this. Spent few hrs today reading through the code, but in terms of alt i still cant figure out how the handler fn callback on take! is NOT called (or is kinda rolled back) for the channels that do not end up first (in the race condition). I have done this kinda implementation few times in past, but alt i always coded myself because of this. I originally thought the mutex between channels is shared, but it does not seem so; the alt-flag locking also does not seem to do the job.... <@Sandy> if there is no available library but you still could point me to the right namespace and line of code that addresses this that would be very much appreciated ... i should be (edit: hopefully) able to figure out the rest.... | 2017-12-18T11:51:45.000718 | Particia |
clojurians | clojure | <@Particia> one way or another it would be great to have this as a library | 2017-12-18T12:00:09.000573 | Twanna |
clojurians | clojure | The potentials are huge | 2017-12-18T12:00:25.000343 | Twanna |
clojurians | clojure | hey folks, I want to create a series of videos in order to tech clojure in my local language to those who are interested. | 2017-12-18T12:01:29.000523 | Darcel |
clojurians | clojure | I'm a bit dizzy about the TOC of the course. | 2017-12-18T12:02:43.000133 | Darcel |
clojurians | clojure | do you think that the lisp concepts are important in the beginning ? | 2017-12-18T12:03:18.000570 | Darcel |
clojurians | clojure | or do you know a good presentation or a course in English which i get inspiration from ? | 2017-12-18T12:05:15.000383 | Darcel |
clojurians | clojure | <@Particia> I would recommend thinking about the relationship between the queue and the channels. What do you want to happen if a message is 3 channels deep into your app and the service dies? | 2017-12-18T12:09:09.000065 | Sandy |
clojurians | clojure | What I recommend is instead passing an ack funtion with the message, and then the last thread In your channel chain calls that to tell the queue that the message ha been processed | 2017-12-18T12:10:30.000239 | Sandy |
clojurians | clojure | In short, it’s a mistake to ack the message when it goes onto a channel. Queues are durable, channels are not. | 2017-12-18T12:11:14.000049 | Sandy |
clojurians | clojure | Because `*ns*` is a dynamic var, the “current namespace” is not the one in which the function was defined, it’s the one in which the code is running. If the defn needs to happen in a specific namespace, use `in-ns` to make sure that’s the context. You can also use `intern` which explicitly takes a namespace as an argument. | 2017-12-18T12:21:19.000295 | Margaret |
clojurians | clojure | ```Clojure 1.9.0
(ins)user=> (create-ns 'foo.bar)
#object[clojure.lang.Namespace 0x5443d039 "foo.bar"]
(ins)user=> foo.bar/baz
CompilerException java.lang.RuntimeException: No such var: foo.bar/baz, compiling:(NO_SOURCE_PATH:0:0)
(ins)user=> (intern 'foo.bar 'baz "hello")
#'foo.bar/baz
(ins)user=> foo.bar/baz
"hello"``` | 2017-12-18T12:24:24.000543 | Margaret |
clojurians | clojure | <@Sandy> yes, acking i do once the message is processed, keep that as a function of a message or a session. But what i struggle with is how to leverage existing implementation of alt!!.. I always implemented that myself (usually multiple threads polling/waiting on queues with a use of locking and nacking messages that arrived second) because i couldnt figure out how the take! callback would have to look like so as it would work with the core async alt implementation. So my question is what method in clojure.core.async.impl.protocols.Handler is in charge of the "rollback" in case the alt's take! from a channel finishes second? | 2017-12-18T12:38:22.000608 | Particia |
clojurians | clojure | That’s the problem I think you can avoid. Just keep messages as data and use the default implementations of alt! | 2017-12-18T12:42:38.000020 | Sandy |
clojurians | clojure | Don’t try to do ack as part of an alt! | 2017-12-18T12:43:05.000371 | Sandy |
clojurians | clojure | Not only is it hard to implement, I’m not sure it’s possible to do correctly with a mutable queue. | 2017-12-18T12:43:51.000305 | Sandy |
clojurians | clojure | Thanks guys. This is amazingly useful | 2017-12-18T13:50:31.000552 | Twanna |
clojurians | clojure | <@Darcel> <https://www.braveclojure.com/clojure-for-the-brave-and-true/>
Might want to check out <#C053AK3F9|beginners> and ask around there too | 2017-12-18T14:19:54.000162 | Sharlene |
clojurians | clojure | datomic vs postgres for a simple-ish ecommerce site, what are your opinions? I like the temporal nature of datomic, in that if I update facts older transactions remain valid. Vs changing things in a regular rdbms where it can also change prior transactions if not done right. Also the datalog integration with clojure is really nice. But $5000/yr/system ;( | 2017-12-18T14:23:15.000128 | Williemae |
clojurians | clojure | sql through clojure doesn’t seem great, but maybe I’m missing a critical library that helps out a bit (Is HugSQL any good?) | 2017-12-18T14:24:04.000098 | Williemae |
clojurians | clojure | <@Williemae> HugSQL is great! I’ve been incorporating it into my projects more often lately and I love it! I’m a fan of free so I usually go Postgres but that’s just me | 2017-12-18T14:27:06.000457 | Sharlene |
clojurians | clojure | is using `sut` as name of the system under test when creating test namespaces a bad practice? | 2017-12-18T14:31:19.000309 | Krystina |
clojurians | clojure | that's what cider does by default when creating a new test file, but could not really see anywhere if it's a good practice or not | 2017-12-18T14:31:51.000015 | Krystina |
clojurians | clojure | I do not prefer it, I end up changing it to whatever the pattern is for that ns in the rest of the program | 2017-12-18T14:33:29.000133 | Mia |
clojurians | clojure | e.g. `myapp.thing :as sut` -> `myapp.thing :as thing` | 2017-12-18T14:33:59.000698 | Mia |
clojurians | clojure | so I can more easily grep for usages of `thing/foo` and other reasons | 2017-12-18T14:34:38.000248 | Mia |
clojurians | clojure | yeah I also prefer not to use it for that reason | 2017-12-18T14:39:58.000396 | Krystina |
clojurians | clojure | <@Williemae> checkout also `honeySQL` ! | 2017-12-18T14:45:04.000064 | Amado |
clojurians | clojure | cool, thanks for the suggestion. I’ll be doing most stuff in stored procs (if I go with postgres) but this looks like a great option for executing those. | 2017-12-18T14:46:09.000155 | Williemae |
clojurians | clojure | er well i guess postgres is a bit different from the last time i did a sql database lol, i see they dont really do stored procs. So nevermind that then! | 2017-12-18T14:47:16.000093 | Williemae |
clojurians | clojure | hello everyone, im trying to generate a fat jar of a main application (its not a webserver it just starts some jobs and then dies), but i keep getting errors
`lein with-profile dev uberjar` produces:
java.lang.IllegalArgumentException: env variable ‘:db-host’ is not set, compiling:(cfg.clj:17:1)
I have a profiles.clj populated with the right env variables, it does work while working inside the repl | 2017-12-18T14:47:24.000587 | Amado |
clojurians | clojure | <@Williemae> they do! <http://www.sqlines.com/postgresql/stored_procedures_functions> | 2017-12-18T14:47:51.000198 | Amado |
clojurians | clojure | ah great….seems my google-fu is weak today | 2017-12-18T14:48:05.000362 | Williemae |
clojurians | clojure | ```
;; foo.cljc
(ns foo (:require [clojure.spec.alpha :as s]))
(defmacro tm [& lst] `(s/def ~@lst))
;; bar.cljc
(ns bar (:require [foo])) ;; notice, we don't alias spec.alpha
(macroexpand-1 '(foo/tm 1 2 3)) ==> (clojure.spec.alpha/def 1 2 3)
```
so it appears the `s/def` is being expanded at DEF MACRO time, not at USE MACRO time. I find this counter intuitive. Can someone explain the machanics by which this is happening ?
[ I was expecintg an error saying there is no such namespace in ns bar ] | 2017-12-18T15:01:32.000022 | Berry |
clojurians | clojure | macros are expanded at macroexpansion time | 2017-12-18T15:08:33.000424 | Aldo |
clojurians | clojure | if you want to expand them at runtime then you need eval | 2017-12-18T15:08:53.000356 | Aldo |
clojurians | clojure | In order to avoid capturing and re-using some symbol in `bar`, ordinary symbols are expanded before you leave `foo`. You would need ```(defmacro tm2 [& lst] `(~'s/def ~@lst))``` to quote the use of `s/def` to carry that over and pick up whatever that meant in the environment you are expanding in (here, `bar`) | 2017-12-18T15:08:56.000159 | Heide |
clojurians | clojure | <@Aldo>: is 'macroexpansion' time (1) when macro is defined or (2) when macro is used ? | 2017-12-18T15:10:49.000079 | Berry |
clojurians | clojure | oh, except the time of expansion is not your issue here. like lukswater said you're just expecting ` to work differently to how it does | 2017-12-18T15:10:59.000616 | Aldo |
clojurians | clojure | <@Heide>: I see the ```
`(~'s/def
```
trick now, thanks! | 2017-12-18T15:11:30.000415 | Berry |
clojurians | clojure | ` syntax-quotes a bunch of stuff given the context of its definition | 2017-12-18T15:11:35.000109 | Aldo |
clojurians | clojure | Somewhere there’s an extensive essay on quoting in Clojure macros | 2017-12-18T15:11:51.000501 | Heide |
clojurians | clojure | I'm sure there is, but it's the type of dry stuff that I don't expect to understand until I run into issues of "I expect FOO, but I got BAR" | 2017-12-18T15:12:31.001224 | Berry |
clojurians | clojure | I believe this is it: <https://8thlight.com/blog/colin-jones/2012/05/22/quoting-without-confusion.html> | 2017-12-18T15:13:59.000233 | Heide |
clojurians | clojure | thanks! | 2017-12-18T15:15:41.000037 | Berry |
clojurians | clojure | <@Elizbeth> I was trying to do a DFS in clojure recently and had a similar problem; it didn't seem natural to recur in tail call position.
I found an answer in Stuart Sierra's dependency library, it's a little bit terse but way more elegant than anything I came up with.
```
(defn- transitive
"Recursively expands the set of dependency relationships starting
at (get neighbors x), for each x in node-set"
[neighbors node-set]
(loop [unexpanded (mapcat neighbors node-set)
expanded #{}]
(if-let [[node & more] (seq unexpanded)]
(if (contains? expanded node)
(recur more expanded)
(recur (concat more (neighbors node))
(conj expanded node)))
expanded)))
``` | 2017-12-18T15:24:29.000458 | Kristan |
clojurians | clojure | that's actually very neat | 2017-12-18T15:53:10.000440 | Elizbeth |
clojurians | clojure | i need to examine it a bit more closely to understand it fully | 2017-12-18T15:53:39.000728 | Elizbeth |
clojurians | clojure | thanks :slightly_smiling_face: | 2017-12-18T15:54:02.000019 | Elizbeth |
clojurians | clojure | reminds me of some examples in the Little schemer | 2017-12-18T15:54:33.000250 | Elizbeth |
clojurians | clojure | Oh I need to get that book, was tempted recently because the MIT Press had a 40% off black friday sale | 2017-12-18T16:29:02.000616 | Kristan |
clojurians | clojure | <@Timika>: Great Codemesh talk - I'm loving all of your recent Datomic outreach efforts. | 2017-12-18T17:00:08.000311 | Rene |
clojurians | clojure | thanks | 2017-12-18T17:02:23.000149 | Timika |
clojurians | clojure | Can somebody explain this to me please? | 2017-12-18T17:18:21.000227 | Augusta |
clojurians | clojure | both on cljs (lumo) and the JVM | 2017-12-18T17:18:42.000207 | Augusta |
clojurians | clojure | and | 2017-12-18T17:18:46.000449 | Augusta |
clojurians | clojure | Here's a link to the talk for anyone interested: <https://www.youtube.com/watch?v=nbMMywfBXic> | 2017-12-18T17:22:07.000143 | Afton |
clojurians | clojure | it looks like clojurescript is confusing reduce and transduce somewhere | 2017-12-18T17:26:37.000247 | Rebeca |
clojurians | clojure | the first example has a one item collection and the second has two items | 2017-12-18T17:27:45.000399 | Jonas |
clojurians | clojure | the first example will never use the function to combine elements | 2017-12-18T17:28:07.000089 | Jonas |
clojurians | clojure | because there is only one element | 2017-12-18T17:28:12.000065 | Jonas |
clojurians | clojure | whereas the second example will | 2017-12-18T17:28:23.000213 | Jonas |
clojurians | clojure | (yeah, I misread that) | 2017-12-18T17:28:39.000555 | Rebeca |
clojurians | clojure | <@Augusta> that behavior is explicit in `reduce`'s docstring | 2017-12-18T17:29:43.000479 | Kareen |
clojurians | clojure | `If coll has only 1 item, it is returned and f is not called.` | 2017-12-18T17:29:54.000137 | Kareen |
clojurians | clojure | I understand that boot/lein uses JVM. I understand that Macro system uses JVM. Right now, in Clojure dev, I use cider to talk to a JVM repl -- is there anyway to make it practical to talk to a node.js repl instead ? | 2017-12-18T17:29:55.000085 | Berry |
clojurians | clojure | i think you want `inf-clojure` | 2017-12-18T18:09:26.000221 | Willow |
clojurians | clojure | No, I'm not after an emacs mode. | 2017-12-18T18:22:43.000162 | Berry |
clojurians | clojure | CIDER is basically nREPL middleware so it's JVM only. Can you explain what you think you want to connect to a Node.js REPL? | 2017-12-18T19:13:41.000235 | Daniell |
clojurians | clojure | <@Berry> Clojurescript projects and tools like <https://github.com/anmonteiro/lumo> will connect (transpile) your Clojurescript code to a node.js host. You can also call node.js libraries. | 2017-12-18T19:29:56.000335 | Evie |
clojurians | clojure | Socket repls are completely possible. | 2017-12-18T19:40:53.000069 | Sandy |
clojurians | clojure | lumo and planck both support socket repls. As does the CLR. | 2017-12-18T19:41:38.000094 | Sandy |
clojurians | clojure | <@Daniell>: my current setup is client side = cljs; server side = clj via jvm ;; I am considering changing server side to cljs via nodejs | 2017-12-18T22:05:30.000147 | Berry |
clojurians | clojure | but it's not clear to me how to get a 'cljs repl on nodejs' on the server side | 2017-12-18T22:05:44.000147 | Berry |
clojurians | clojure | <@Sandy>: are those meant as dev environments, or a way to write shell scripts in cljs ? | 2017-12-18T22:06:03.000241 | Berry |
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