^ +1 to that. It's pleasantly surprising how cheap short-living garbage is on modern VMs.

Why some of the functions defined this way?

(def
 ^{:arglists '([x])
   :doc "Return true if x is a String"
   :added "1.0"
   :static true}
 string? (fn ^:static string? [x] (instance? String x)))

i'm not sure if this one in particular is due to this but you might be seeing workarounds to the bootstrap problem. If defn hasn't been defined yet then you can't use that form. And i imagine that defn uses string? so this must come before that

@dpsutton thanks, seems logical

This is a bit algorithmic-specific rather than Clojure-specific but I'm new to functional/clojure and that's making this extra difficult. I'm trying to create a seq of all combinations of sublists of a list. So [1 2 3] becomes [ [[1] [2] [3]], [[1] [2 3]], [[1 2] [3]], [[1 2 3]] ]

Are you looking for a library that has a function that does that, or are you looking to write a function yourself?

@ericihli https://github.com/clojure/math.combinatorics/blob/master/src/main/clojure/clojure/math/combinatorics.cljc

Idan, I'm curious how it's done. If there's a library, that's enough I could read the implementation and get a little bit of an understanding. Ivan, I looked at the combinatorics library and couldn't find the answer there. It's not quite subsets because order and position matters. For example, I can't have [1 3] or [2 1] in my result set from [1 2 3] input.

Maybe partitions would be a better choice for you than?

From the combinatorics GitHub page:

=> (combo/partitions [1 1 2])
(([1 1 2])
 ([1 1] [2])
 ([1 2] [1])
 ([1] [1] [2]))

That's totally it! Thanks! I even freaking saw function in there about 2 hours ago and it didn't register that it was what I was looking for and I spent the next two hours trying to figure it out.

Ah I think I know what happened. I scanned the list of functions in combinatorics, I saw "partition" and thought that might be it, so I googled "clojure partition" and saw https://clojuredocs.org/clojure.core/partition and that's totally not it.

Bah. No. Even that's not quite right.

(combo/partitions [1 2 3])
(([1 2 3]) ([1 2] [3]) ([1 3] [2]) ([1] [2 3]) ([1] [2] [3]))

...as a quick fix. Still eventually want to figure out the proper algorithm.

@ericihli permutations creates a lazy sequence of calls to iter-perm function in one or another way

well, i was a bit wrong here, authors redirect us to a book

Most of these algorithms are derived from algorithms found in Knuth's wonderful Art of Computer Programming books (specifically, the volume 4 fascicles), which present fast, iterative solutions to these common combinatorial problems.  Unfortunately, these iterative versions are somewhat inscrutable.  If you want to better understand these algorithms, the Knuth books are the place to start.

Hi all. How to require spec defined in another file (namespace) with

(s/def ::my-string string?)

This seems to work:

(s/valid? ::hs/my-string word)

hs

Nope, that’s good

thx Alex

TL;DR - Need help with deploying a shadow-cljs project to heroku. Would anyone be able to answer some questions about deployment to heroku? I have a test project here: https://github.com/andreortiz82/middlemancljs I’m trying to deploy it to heroku but I’m not sure what the incantations are. * What build packs do I need? Ruby, Node, Java - all of them? * What should the Procfile contain? * Who the heck sent me down this wacky path in the first place?! 👉 this guy @bobnadler (only slightly kidding 😉 ) If anyone has the time to assist (or sync on a zoom call) - that would be great!

Where should we ask jdk questions? I've been trying out adoptopenjdk with openjdk 11. I am also exploring graalvm so installed the community edition and put that in my path. Now (on linux debian) whichever export statement I have last in my .profile turns into my default jdk. If graalvm path is last then my java -version is java 8 graalvm with no mention of adoptopenjdk. vice versa with java 11 if i have adoptopenjdk last. How does this affect my clojure software development? Are these two going to coincide peacefully or will my various projects be all screwed up depending on which one I used to start a project or run a project? Sorry if this is too convoluted.

you can have these coexist, you can treat them as separate JDKs

Some parts of graal like native image are not officially supported by clojure

ok cool. I think I will just keep adoptopenjdk 11 as my default and try to bring graalvm to the forefront whenever I want to explore creating a native binary. Which is different than the "native image" thing you just mentioned right? I was thinking the whole benefit of clojure folks trying graalvm was to compile to native binaries.

native-image is "Not Java"

you're going to run into brick walls every other minute

lots of restrictions, some parts of the JDK are not supported

if you want something that is supported try jaotc, it's part of the JDK

both are a pain in the ass to use, but jaotc is Real Java

it produces native binaries

Has anyone here had a good experience with the http://purelyfunctional.tv service? I think I am going to drop for the membership but just want to hear a testimonial to put my mind at ease first

anyone got a minute to assist with cider nrepl issues ?

What's the issue? I'm not at my machine but I think usually the issues are related to versioning

i'm using nrepl 0.6.0 and cider/cider-nrepl "0.22.0.beta1"

which seem to be the latest

my emacs cider is 0.22.0snapshot

which seems to be most recent versions of everything

i'm trying to embed a repl , build and run an uberjar, and connect to it

the connection from emacs happens (with cider-connect-clj)

and it doesn't complain about version mismatch or anything

but the clj app throws a bunch of exceptions

i launched the repl server like this:

(:require  [nrepl.server :as nrepl-server] 
  [cider.nrepl :as cider]) 

 (nrepl-server/start-server :port 7888 :handler cider/cider-nrepl-handler) 

but it can't find namespaces , hangs on eval buffer, throws exceptions like this:

ERROR: Unhandled REPL handler exception processing message {:op complete, :ns user, :symbol co, :context :same, :session 6e561eda-b8f2-400d-b1c6-67485763e6d5, :id 10}
java.lang.NullPointerException

any thoughts ?

can you share more of the stacktrace?

the only unusual thing i'm doing is including compiled classes for grpc stuff

sure

ERROR: Unhandled REPL handler exception processing message {:op out-subscribe, :session 4c15cf3a-fd34-4464-9c70-8c07c8367587, :id 5}
java.lang.NullPointerException
        at clojure.core$deref_future.invokeStatic(core.clj:2300)
        at clojure.core$deref.invokeStatic(core.clj:2320)
        at clojure.core$deref.invoke(core.clj:2306)
        at cider.nrepl$wrap_out$fn__10724.invoke(nrepl.clj:290)
        at nrepl.middleware$wrap_conj_descriptor$fn__10059.invoke(middleware.clj:16)
        at cider.nrepl$wrap_enlighten$fn__10686.invoke(nrepl.clj:162)
        at nrepl.middleware$wrap_conj_descriptor$fn__10059.invoke(middleware.clj:16)
        at cider.nrepl$wrap_refresh$fn__10736.invoke(nrepl.clj:336)
        at nrepl.middleware$wrap_conj_descriptor$fn__10059.invoke(middleware.clj:16)
        at cider.nrepl$wrap_tracker$fn__10772.invoke(nrepl.clj:437)
        at nrepl.middleware$wrap_conj_descriptor$fn__10059.invoke(middleware.clj:16)
        at nrepl.middleware.session$session$fn__10452.invoke(session.clj:272)
        at nrepl.middleware$wrap_conj_descriptor$fn__10059.invoke(middleware.clj:16)
        at nrepl.middleware.print$wrap_print$fn__10259.invoke(print.clj:234)
        at nrepl.middleware$wrap_conj_descriptor$fn__10059.invoke(middleware.clj:16)
        at cider.nrepl$wrap_slurp$fn__10654.invoke(nrepl.clj:94)
        at nrepl.middleware$wrap_conj_descriptor$fn__10059.invoke(middleware.clj:16)
        at nrepl.server$handle_STAR_.invokeStatic(server.clj:18)
        at nrepl.server$handle_STAR_.invoke(server.clj:15)
        at nrepl.server$handle$fn__10483.invoke(server.clj:27)
        at clojure.core$binding_conveyor_fn$fn__5739.invoke(core.clj:2030)
        at clojure.lang.AFn.call(AFn.java:18)
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
        at java.base/java.lang.Thread.run(Thread.java:834)
ERROR: Unhandled REPL handler exception processing message {:nrepl.middleware.print/stream? 1, :nrepl.middleware.print/print cider.nrepl.pprint/pprint, :nrepl.middleware.print/quota 1048576, :nrepl.middleware.print/options {:right-margin 70}, :op init-debugger, :session 4c15cf3a-fd34-4464-9c70-8c07c8367587, :id 6}
java.lang.NullPointerException
        at clojure.core$deref_future.invokeStatic(core.clj:2300)
        at clojure.core$deref.invokeStatic(core.clj:2320)
        at clojure.core$deref.invoke(core.clj:2306)
        at cider.nrepl$wrap_debug$fn__10680.invoke(nrepl.clj:136)
        at nrepl.middleware$wrap_conj_descriptor$fn__10059.invoke(middleware.clj:16)
        at cider.nrepl$wrap_inspect$fn__10706.invoke(nrepl.clj:199)
        at nrepl.middleware$wrap_conj_descriptor$fn__10059.invoke(middleware.clj:16)
        at cider.nrepl$wrap_trace$fn__10766.invoke(nrepl.clj:419)
        at nrepl.middleware$wrap_conj_descriptor$fn__10059.invoke(middleware.clj:16)
        at cider.nrepl$wrap_macroexpand$fn__10712.invoke(nrepl.clj:243)
        at nrepl.middleware$wrap_conj_descriptor$fn__10059.invoke(middleware.clj:16)
        at cider.nrepl$wrap_spec$fn__10748.invoke(nrepl.clj:374)
        at nrepl.middleware$wrap_conj_descriptor$fn__10059.invoke(middleware.clj:16)
        at nrepl.middleware.load_file$wrap_load_file$fn__10366.invoke(load_file.clj:81)
        at nrepl.middleware$wrap_conj_descriptor$fn__10059.invoke(middleware.clj:16)
        at cider.nrepl$wrap_content_type$fn__10648.invoke(nrepl.clj:82)

it goes on for days like that, i can post it all if that'd help

do you ever get to a java.lang.ClassNotFoundException?

checking

nope, all null pointer exceptions

gotcha - I was seeing if this was a nrepl-related issue that was fixed relatively recently with a new snapshot release, but it seems like that's not the case here. unfortunately I don't know enough to help further!

no worries, thanks for giving it a try :thumbsup:

i can fall back to my old workflow - just the classpath stuff with grpc/proto has me recompiling and it kills the repl workflow

so I’m trying to re-create your error, and I when I use cider-nrepl 0.21.1, it works fine

i only started having trouble when i wanted to embed the repl in the jar and connect that way, instead of cider-jack-in

I’m not uberjaring anything tho

what if you build uberjar and launch embedded repl server ?

let me give it a try with 0.21.1 also

do you know how to force emacs to use older version of cider?

WARNING: CIDER 0.22.0-snapshot requires cider-nrepl 0.22.0-beta1, but you're currently using cider\
                                                                                                   |-nrepl 0.21.1. The version mismatch might break some functionality!

same exceptions and behavior (frozen repl) , regardless

How can I run single .clj file without Leiningen? I tried java -cp clojure.jar clojure.main test-code.clj but got an error: "Error: Could not find or load main class clojure.main" I tried to find clojure.jar (and even clojure*.jar) on my machine and there is none. I installed Clojure with Leiningen (downloaded lein.sh from official site and followed the docs)

for lein, I believe you can do lein run -m clojure.main test-code.clj

lein uses the Maven dependency cache in ~/.m2/repository and so the main clojure jar will be buried in that cache, along with any other dependencies you use.

I don't want to use Leiningen in this case because of it's startup time

the main clojure jar has two dependencies as well, so it's slightly more complicated to use it directly

would clojure /path/to/file.clj not work? Am I mistaken?

you may be interested in the clj tool as well

https://clojure.org/guides/getting_started

@mitchell_clojure it can work if Clojure is installed with standard package manager

clj is a dependency downloader, classpath constructor, and wrapper around clojure.main

i think you can use boot and shebang notation to kick off a clojure file but the clojure.jar still needs to load

like

#!/usr/bin/env boot

(defn -main ....)

then chmod +x it

Ok, I did sudo apt install clojure which gave me clojure binary and it's version 1.9. Now I can do clojure my-code.clj

I didn't know Ubuntu has the latest Clojure in the repo

I'm not sure what that clojure script you're getting is

can you do clojure -Sverbose ?

if that works, then that's cool. if it doesn't, then that's some non-official script being included with the distribution.

also, since you mentioned startup time; if you don't need jvm ecosystem, you may be interested in cljs/node alternative planck for scripting

actually to correct myself planck doesn't depend on node

Right, Planck uses JavaScriptCore, Lumo uses V8, but effectively is a special build of Node

BTW, is Clojure on .NET mature? Can it work on .NET Core ?

you're asking about the Clojure CLR project?

oh, yes. Just forgot correct name

https://github.com/clojure/clojure-clr

i haven't used it, myself

@gr.evocatus If you're up for listening to a podcast, https://vijaykiran.com/2019/04/defn-48-david-miller/ has the best recent overview of everything you might want to know about it before using it

Thanks 🙂

ClojureCLR is basically up to date with the jvm version (David Miller was working on 1.10.0 compatibility)

It's great !

Looks like there are enough differences between JVM and JS to be extremely careful while prototyping on Planck/Lumo. Even numbers are represented differently (JS doesn't have actual Long Integers)

somewhere there is an incomplete and always growing list of differences between clojure and clojurescript

https://clojurescript.org/about/differences

Does anyone have tips for profiling slow leiningen start up times? I am on a fresh machine, running same java version and lein version as rest of my team, yet start up times are almost double than theirs.

I had to set a large timeout in my profiles.clj to load the same project, otherwise it times out

the first thing to do is to examine the differences between your setup and other people on the team's setup

configuration from sources that don't often get checked in, like a user.clj or profiles.clj, are likely contenders

Hm yeah I did compare profiles.clj

i wonder if maybe it's a network issue with our private maven repo

what timeout option do you need to set?

there is a known performance issue with the latest version of the jdk that has a drastic perf impact if you are using a user.clj file

{:user
  {:repl-options {:timeout 120000}}}

what's your java -version and do you have a user.clj file?

that has nothing to do with fetching deps from maven

fetching deps happens after loading right? I do not have a user.clj, using java 1.8.0_202 and lein 2.9.1

java 1.8.0_202 is the first Java 8 build with the issue (also 11.0.2, 12)

lein runs two jvms, one for lein one for your project, the repl client runs in the lein jvm and the server runs in the project jvm

ahhh okay

that timeout is how long the client waits for connecting to the server

so that indicates the project jvm is slow to start, which sounds like you have a user.clj somewhere

don't think i have a user.clj, i never created one

but let me verify

you can verify if there is a rogue one on your classpath by running ( "user.clj")

thank you

if you don't find one, it's probably just bloated dependencies or plugins

there's definitely bloat

oh yeah, if you have any plugins get rid of them

but not sure why my machine would take more than twice as long to start up

plugins can literally do anything

so they could just sleep for 10 seconds if the hostname doesn't match a regex

there is a user.clj in the module itself

checked with ( "user.clj") per @ghadi I think that solves it

what's in the file?

and what do you mean by "module"

sorry the project directory

project/project.clj, project/env/dev/user.clj

nix it and watch the performance come back

whoops

we are working on a dodge around this issue for 1.10.1

excellent, thanks everyone for the help

should be able to drop in the 1.10 beta and see an improvement if so, right?

yes, 1.10.1-beta2 is available now

(soon to be beta3)

Is it possible to use something like pattern matching in multimethods (or build a new multimethod implementation around pattern matching)? I'd like to do something like the following:

(defmatchmulti mm [a b] [a b])
(defmatchmethod mm [1 2] [a b] :a1)
(defmatchmethod mm [_ 2] [a b] :a2)
(defmatchmethod mm [1 _] [a b] :a3)
(defmatchmethod mm :default [a b] :a4)

(mm 1 2) ;; => :a1
(mm 3 2) ;; => :a2
(mm 12 104) ;; => :a4

I'm working on implementing something that translates underscores to ::no-match and does the comparison at runtime, but it seems a bit brute-forcey

Clojure Gurus! I yesterday asked how to convert this:

[{:pgid {:S "1"}, :pgname {:S "Books-local-aws"}} {:pgid {:S "2"}, :pgname {:S "Movies-local-aws"}}]

{"1" "Books-local-aws", "2" "Movies-local-aws"}

(reduce
    (fn
      [mymap item]
      (assoc mymap
        (-> item :pgid :S) (-> item :pgname :S)))
    {}
    items)

(->> items
         (map (juxt (comp :S :pgid) (comp :S :pgname)))
         (into {}))

The first I find easier to read, but the second is cooler (I didn’t know juxt!). I like to go with the code that is the “least surprising” so that would be 1.

That said, wrap your implementation in a function, add a docstring, write a test, and they are equal from a usage perspective 🙂

... and is there some way to "reverse-engineer" some expressions like

(juxt (comp :S :pgid) (comp :S :pgname))

@kari.marttila in my experience, reading the doc strings for juxt, comp, partial, and apply, then translating as many functions as I can into "point free" style as I can with repl experimentation

the idea with point-free is that you eliminate variable names from the code, and those functions in particular allow a specific style of point-free code when used together

and after enough experimentation and forced examples, it gets easier to recognize cases where they will simplify your code

(and along with that, it gets easier to recognize the point free idioms when reading code)

also, learning about lambda calculus might help if you like higher math, or are fond of that style of reasoning

Ok. Thanks. Practice, practice, practice.

Work hard Kari!

haha, and take time in a hammock every now and then 🙂!

All work and no play makes Kari a dull boy. 

What's hammock?

BTW. These video recommendations are really good. Every time someone recommends a Clojure related video I send an email to myself to remind me to watch the video (my inbox - a kind of task list). E.g. Stuart Halloway's REPL Driven Development was astonishing. I also started to write my REPL stuff in a file instead of REPL editor. I already have a bunch of various expression experiments in my scratch file. All these expressions would have disappeared like tears in rain if I had used REPL editor - now they are eternally in my scratch file for me to browse them through later time to see if I have done something similar in the past.

you can also make watch lists on YT

There is a big list of talks here: https://github.com/tallesl/Rich-Hickey-fanclub

Great! Another email sent to me!

@kari.marttila I usually accompany reading the docstrings with exercising the expressions with simplest possible examples.

user> ((juxt inc dec) 1)
[2 0]

user> (map (juxt inc dec) [1 2 3])
([2 0] [3 1] [4 2])

user> (into {} (map (juxt inc dec) [1 2 3]))
{2 0, 3 1, 4 2}

for juxt, I find it's helpful to think of it as opposed to map - map applies the same function to many pieces of data. juxt applies many functions to the same data. (with the difference that juxt returns a function rather than doing the work itsefl)

Good point that juxt can apply any amount of functions

user> ((juxt inc dec str -) 1)
[2 0 "1" -1]

Here is a handy usage of juxt in a higher order function that I keep in my utility belt:

(defn index-by
  ([idx-fn coll]
   (index-by idx-fn identity coll))
  ([idx-fn value-fn coll]
   (into {} (map (juxt idx-fn value-fn)) coll)))

(def ms [{:id 1 :name "kissa"} {:id 2 :name "koira"}])

user> (index-by :id ms)
{1 {:id 1, :name "kissa"}, 2 {:id 2, :name "koira"}}

user> (index-by :id :name ms)
{1 "kissa", 2 "koira"}

user> (index-by (comp str :id) (comp string/upper-case :name) ms)
{"1" "KISSA", "2" "KOIRA"}

As a side note index-by is a ‘less generic version’ of core function group-by

i really think that index-by should throw on duplicate keys

side note, I know

Yeah there’s a caveat. Good point. 😉

the version I use:

(defn index-by
  ([keyf coll]
   (index-by keyf identity coll))
  ([keyf valf coll]
   (reduce (fn [m v]
             (let [k (keyf v)]
               (if (find m k)
                 (throw (ex-info "Duplicate key" {:k k}))
                 (assoc m k (valf v)))))
           {}
           coll))
  ([keyf valf mergef coll]
   (reduce (fn [m v]
            (let [k (keyf v)]
               (if-let [entry (find m k)]
                 (assoc m k (mergef (val entry) (valf v)))
                 (assoc m k (valf v)))))
           {}
           coll)))

(mimics https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/stream/Collectors.html#toMap(java.util.function.Function,java.util.function.Function) )

That’s definitely more solid but but… the aesthetics… 😄

i'm not trying to date my code 😂

Fair

I'm following these instructions : https://clojurescript.org/guides/quick-start to get a repl running in a browser. Everything seems to work except that I don't get a repl prompt in the browser window. Does anyone have any thoughts on what might be going wrong or how to diagnose the problem?

I didn't think that was supposed to have a repl in the browser itself - usually a cljs repl is in a terminal and talks to the browser over a socket

> After a couple of seconds you will see Hello world! print at the terminal and you will be given a REPL prompt. Try evaluating some expressions like the following: to me, that means "enter these things into the terminal"

I do see the "Hello world!" printout but no prompt at the terminal either. When I type into the terminal I get no repsonse.

I would be happy with a repl in either the browser or the terminal.

The message in the browser window says "This page hosts your REPL and application evaluation environment. " which gave me the impression that the REPL would appear on the page but I don't really care one way or the other.

The "developer console" built into the browser is like a JS repl, but it's not usually the repl we're talking about when talking about clojure repls. We'll usually be referring to the terminal repl (or one connected from your IDE)

But if you follow the quick-start guide, you should have gotten a prompt at the terminal repl

no prompt at the terminal repl.

just a "Hello World!" message

and a browser window popped up as the instructions said would happen.

does it say the clojurescript version, right under the "Hello world!" message in the terminal?

no, nothing.

The "hello world!" message prints again if I refresh the browser window.

Are there any messages in the developer console? (the one within the browser)

Did you remember to pass the flag to enable the repl at the end? clj --main cljs.main --compile hello-world.core --repl

no messages in the browser console.

here's what I see in the terminal:

Hi. I have two vectors: 1. - [ [Z1 X1 C1] [Z2 X2 C2], .....[Zn Xn Cn] ] 2. - [ [Q1] [X1] [W1] [Q2] [X2] [W2] [Qm] [Xm] [Wm] ] m != n The names Z X C .... are fields with some type (type in domain, not in programming - all of theme are strings) I want to combine those two vectors into one if they match pattern that field X in first vector is the same a field X in the second vector. I'm looking for a hint how to do it not for a solution. Do any one know how to do it in Clojure?

( I think slack didn't like what I typed in )

/repos/gitnc/hello-world$ clj --main cljs.main --compile hello-world.core --repl Hello world! Hello world!

merge-with is a start

@davecompton7 That's strange :thinking_face:

In OO language (or just not Clojure) I will make two loops (O(n2)) compare values and merge theme...

Is there any kind of error log or something along those lines that I can look at?

I'm a little at a loss for where to go from here.

Well, the ordering of things don't appear to be guaranteed actually, so I'm not sure if you'll want to start with merge-with there

@john (mege-with function_which_check_condition vector1 vector2) - will it be something like this?

@davecompton7 Have you tried starting fresh from another folder entirely?

you mean another directory in the filesystem ?

@tomek423 Yeah, but that'd assume your values in both vectors are aligned

I'm not sure how you plan to match up which groups belong to which, between vectors

@davecompton7 yeah, just to make sure it's a fresh development environment

@john What do you mean by aligned? They are always on the same indexes in both files.

So then, you should be able to partition the second vector by 3, and then feed both into merge-with

I made vectors from csv file.

I have not tried that yet. I will. I did try deleting the "out" folder that clj created in my "hello-world" folder and then starting again but that didn't help. I'll try starting fresh from a new folder now and let you know if that makes a difference.

I'm not sure about how W and C are playing together there though

@john Thank you I will try to play with (merge-with ...)

@davecompton7 there's also a ./.cpcache folder that you can clear out too

np

@john As a result I want to get [[Z1 X1 C1 Qx Wx] [Z2 X2 C2 Qy Wy] ....]

@john The X is just an email address, and in one vector I have some data an in another I have another part of data related with the first vector by email value.

@tomek423 clojure.set/project isn't the exact thing you want, but I think it would do most of your work for you if you shape your data into what it can use

started over completely from scratch and it made no difference.

@davecompton7 you may have some local environment issues. I gotta run though!

@noisesmith I just looked at the examples of clojure.set/project and they are based on hashMap. Will it work on vectors?

thank you for giving it some thought. Does anyone else have any thoughts on what the problem might be ( or how to diagnose it ).

Really, the "how to diagnose it" is the more important part of my question.

why is intellij the size of wisconsin?

I really hope that’s rhetorical.

like "boy, is that delicious?"

I’d generally right that as an exclamation, with ‘!’ instead of ‘?’

Is there a succinct and idiomatic way of pulling static java methods into a clojure namespace as functions. Tried the following (def int2hex (partial Integer/toHexString)) Unable to find static field: toHexString in class java.lang.Integer

I just meant rhetorical in the sense that it doesn’t expect an actual answer

@kbosompem I don’t think partial works with static Java methods. you might have to use #(Integer/toHexString %)

because (Klass/staticMethod …) is actually a macro

@kbosompem idiomatic way is to use it directly

@penryu memfn works on instance methods but not static methods and its a macro

that's an interesting question. I'm not sure its actually a macro. Fun to go spelunking why this is the case. Its thinking its a field and rightly not finding it

It’s not a macro, it’s the . special form

Which works with both fields and methods and will report as a field error if not found

Back to the original question, no there is no static import

Well, in the sense that (Integer/toHexString ...) expands to (. Integer toHexString …). But the expanded form also can’t be partialed, so… as @alexmiller: no static import — invoke directly or wrap in a lambda.

It is possible to macro the creation of anonymous functions for multiple static methods in one step

Back in old contrib, Stuart Sierra had some stuff for this

I see the code in Compiler.java which creates StaticMethodExpr, InstanceMethodExpr, StaticFieldExpr, or InstanceFieldExpr. Where does the rewriting happen to the special form .. Is that in the reader?

@dpsutton in HostExpr parser i guess

that's what i was seeing already but it seems to already be in (. Integer toHexString) form there

at compile time, when bytecode is being generated, so after reading but before evaluation i guess

it's read by the reader as a list invoking a symbol

the compiler is the one that handles it

thanks @alexmiller. super helpful and informative as always

technically, I think it's in the analyzer part of the compiler where it decides what kind of symbol it is, like in analyzeSymbol

that figures out if it's a var, static call, class, etc

Is there an idiomatic/built in way to perform an instance? with multiple possible classes? In this case I am checking if an exception I have been handed is one of several different possible classes

nothing but the obvious

Java has syntax for that now, but we haven't done anything in Clojure to handle it

typically you'd make multiple catch blocks for each option

maybe a possible future extension to echo Java there

In this case it's outside of a catch (dealing with exceptions coming in from a clj-http.client async call)

some it is

@robertfrederickwarner supers returns a set, and you can easily check if various classes are in it

eg. check set/intersection to do multiple matches in one direction, set/contains in the other direction

Is there any way to find out what namespace is requiring the current one? My use case is I have a namespace (a) that registers a bunch of multimethod handlers that come from namespace (b), but doesn't really export anything. I want to make sure those handlers get registered whatever the calling context, so I'm re-exporting the multimethod from (a). I'd like to enforce the convention that that multimethod is only imported from (a), not from (b). If there's a better way to do this, feel free to suggest it 🙂

create a service provider interface namespace, but your defmethods in there, create implementation namespaces, and if needed create a namespace that pulls in both spi and implementations and defines functions that call the spi

creates a diamond structure