Hello, i’m struggling on something:

(do
  (refer 'clojure.core :exclude '[cat])
  (def cat 0))

if you're evaluating that in the context of a namespace that already imported clojure.core, yes

thank you, do you know how can i evaluate something before importing clojure.core? I’ve got namespaces that (load ...) files after the ns form and those loaded files are containing the previously posted form.

you probably want to load those files in the context of a temporary namespace that doesn't import clojure.core

ok i will think about a way to do that, thank you for your help.

Is there any good alternative to buddy for signing JWTs?

when writing a macro, is there a way to say if x emit symbol else emit nothing

@roklenarcic you have to return a valid clojure expression - nil at the very least

what is your use case?

solved it

~@ with nil

can someone tell how to use media query css at fulcro?

@veddha.riady i've answered this in a thread at #beginners

is (doseq...) done async?

no it's eager

Do I remember correctly someone observing that Clojure Applied uses records fairly heavily? I'm trying to remember what Alex said about that (and whether he's changed his position any since writing that)? (I don't want to @ him right now since he doesn't show "green")

I'm trying to find the size in some multiple of bytes of given objects and was trying to use Java's Instrumentation class but was having some trouble. Is there a better approach to this? I'm hoping to be able to log the size of ingested data into a system for metric purposes

does anyone have any working examples of building an async api web project? i'm cool with using aleph, http-kit, ring, compojure, anything, that works and does the basic stuff (send/receive json) and isn't error-prone. i've been trying to get an async web server up and running for the past 2-3 days and the experience has been pretty terrible

have you looked at pedestal?

the only async webserver stuff I've done was built on top of https://github.com/mrniko/netty-socketio which was a requirement because using socket io was a requirement, but that required a lot of building up to get anywhere. free of the socket io requirement I think I would start with pedestal

for what its worth, the difference between synchronous ring/compojure and async pedestal is not much per the web frameworks benchmarks game.

anyone know a good POS tagger for clojure?

nvm found a few

https://clojurians.slack.com/archives/C03S1KBA2/p1535045799000100 still curious if anybody has experience with this

Hey! If anyone have a idea: https://stackoverflow.com/questions/51993246/a-cond-threading-macro-alternative-that-refers-last-threaded-state-inside-pred

Maybe with this syntax?

(let [params {:a 1 :b 1 :c nil :d nil}] 
  (cond$-> params
    (:a $)       (update :b inc)
    (= (:b $) 2) (assoc :c "here")
    (:c $)       (assoc :d "here")))

;;=> {:a 1, :b 2, :c "here", :d "here"}

always wanted that too. kinda like a mix of cond-> and as->

is there a good place to find what the POS tags actually stand for? Like what is RB and CD?

Had to look POS up 🙂

@leontalbot At work we have condp-> and condp->> that thread through the predicate as well as the expression and that's usually enough:

(let [params {:a 1 :b 1 :c nil :d nil}]
  (condp-> params
    :a (update :b inc)
    (as-> p (= (:b p) 2)) (assoc :c "here")
    :c (assoc :d "here")))

nice!

@micahasmith Maybe I should just open source our little worldsingles.clojure.extensions namespace... People keep asking for these things 🙂

condp-> -- an extension to cond-> that threads the expression
    through the predicate(s) as well as the result(s).
  condp->> -- an extension to cond->> that threads the expression
    through the predicate(s) as well as the result(s).
  condq -- a version of condp that accepts a unary predicate and omits the
    expr (that condp uses as the second argument to the predicate).
  dissoc-all -- an extension to dissoc that dissoc's a sequence of keys.
  flip -- a companion to partial that allows the first argument to be
    omitted (rather than the trailing arguments). Inspired by Haskell's flip.
  interleave-all -- an extension to interleave that uses all elements
    of the longer sequence argument(s).

@seancorfield oh, yeah definitely. i will very gladly open source our helpers.clj file of misc helpful fns and macros as well. always wonder what those look like at other companies

(and how many bugs we're unaware we have in ours...)

☝️:skin-tone-2: Yes, a very good reason to open source something -- more 👀 on it!

are partial functions (partially applied functions) not as first class as they could be?

rules-engine.core> (replace {"inc" (partial + 1) "0" 0} '("inc" "0"))
(#function[clojure.core/partial/fn--5380] 0)
rules-engine.core> (eval *1)
IllegalArgumentException No matching ctor found for class clojure.core$partial$fn__5380  clojure.lang.Reflector.invokeConstructor (Reflector.java:163)

i was thinking that would work just as this does:

rules-engine.core> (replace {"+" + "1" 1 "2" 2} '("+" "1" "2"))
(#function[clojure.core/+] 1 2)
rules-engine.core> (eval *1)
3

eval works on forms

a function object is not a form

sort of by accident because of this special case in eval it does work for some function objects

(#function[clojure.core/partial/fn--5380] 0) <- that isn't a form?

no

a form would be ((partial + 1) 0)

the fact that (#function[clojure.core/+] 1 2) will eval is an accident?

you are effectively feeding the output of eval into the input of eval, and the domain and range of eval are different

accident is maybe a strong word, unintended consequence of a decisions to support some other features

https://dev.clojure.org/jira/browse/CLJ-2093

https://dev.clojure.org/jira/browse/CLJ-1206?focusedCommentId=42277&amp;page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-42277

so maybe i should be doing it like this:

rules-engine.core> (replace {"inc" '(partial + 1) "0" '0} '("inc" "0"))
((partial + 1) 0)
rules-engine.core> (eval *1)
1

ah, just read the link you sent.