Hello All 👋 I have planned to attend https://inclojure.org/ on Feb14th & 15th and looking for some company 🙂

how do you coordinate the format with coworkers working with cursive and emacs ?

@i we have a styleguide.clj which covers and documents the formatting and we ask every teammember to configure his editor / autoformatting so there’s no changes when applying autoformat to this file

@i lein cljfmt fix via https://github.com/weavejester/cljfmt

seems like an open issue https://github.com/cursive-ide/cursive/issues/1403

Is there an HTTP client library where requests produce core.async channels? If not, would there be interest in such a thing? (and if not, why not?)

(I was experimenting with this some time ago, as a wrapper around http-kit's client library, but haven't pursued it because I don't know whether it's a good idea and whether the support burden of creating a FOSS library is worth it...)

@seancorfield Wouldn't it help to contrib to a lib like clj-http? they have callback style async support https://github.com/dakrone/clj-http#async-http-request and this can be added? Less maintenance burden 🙂

https://github.com/r0man/cljs-http already does return core async chans with the same api too

I have something like this:

(def a {:func some.ns/foo})

You cannot

You have the value some.ns/func was pointing to, you don't have the var some.ns/func which is what the metadata is attached to

I see... maybe I could get all the vars in some.ns, compare their values with (:func a), and see which one matches

You can't get the namespace

To illustrate the problems with what you want to do ask yourself what should happen for

(ns a)

(defn f [])

(ns b)

(def g a/f)

In that case, a/f and b/g are bound to the same object, so assuming you could ask the object, which answer would it give?

My clojure/java is lacking here. A java class a$f?

In some cases, the compiler generates a class name which matches the var name for top level defined functions, but that doesn't address functions that are bound to vars in multiple namespaces, and functions creates other ways like via partial

Ah, I see. I somehow got something that works (at least in the REPL), but I guess it depends on how the initial some.ns/foo was created?

(let [s (-> a
            :func
            class
            str
            (str/replace "class " "")
            (str/replace "$" "/")
            (str/replace "_" "-")
            )]
  (meta (find-var (symbol s))))

And for example, I could delete the a namespace, and the function bound to b/g would still have a class of a$f, which doesn't exist anymore, and doesn't match the only namespace the function is bound to a name in

It is a result of a kind of fundamental mistake in thinking about the relationship between names and the values they access

Honestly, I'm very confused. I'm going to read more carefully https://clojure.org/reference/var and https://clojure.org/reference/reader, are those the correct topics to better understand this?

5 is a value, and might be bound to any number of names in a program

None of which are some how the true name of 5 which you can ask 5 about

Same for the string "foo"

Or any other value

Which functions are

Yes, I understand. I though that clojure would keep some data/metadata about in a about some.ns/foo. I think the better approach would be to simply add the the docstring when initializing a

The doc string lives on the var

So maybe you should use the var instead of the value pointed to by the var

#'some.ns/foo

@dromar56 Try (:doc (meta (resolve 'some.ns/foo)))

What's different between find-var and resolve? Given a fully qualified symbol?

goodday/afternoon/evening, I am looking for the arcadia channel, clojurians working with clojure in the field of gaming?

Was redirected here by someone mentioning I could find one here.

@didibus resolve takes into account namespace aliases and class names:

user=> (require '[clojure.string :as str])
nil
user=> (resolve 'str/join)
#'clojure.string/join
user=> (resolve 'Exception)
java.lang.Exception

Neat, I've just run into the filename length limit of my file system, thanks Clojure compiler...

Doing what?

Compiling a namespace that uses a macro, which results in quite some nesting of functions

yeah, there is a ticket about this

core.match can get you there occasionally

definitely something we'd like to address

Also you'd think that decades into the 21st century, a modern file system like btrfs would allow for longer file names than 255 bytes...

I have a basic question. Why don't I have to require clojure.string but I do have to require other clojure.* libs?:

$ clj
Clojure 1.10.1
user=> (dir clojure.string)
blank?
capitalize
ends-with?
escape
includes?
index-of
join
...
user=> (dir clojure.set)
Execution error at user/eval150 (REPL:1).
No namespace: clojure.set found
user=> (require 'clojure.set)
user=> (dir clojure.set)
difference
index
intersection
join
...

because clojure.core loads clojure.string, somewhat unnecessarily

(there's a ticket about this)

gotcha, thanks

you should not ever rely on any namespace being loaded (except clojure.core, which is auto-required)

I figured, was just puzzled why that ns worked

(clj-kondo warns about not explicitly required namespaces since a release or two ago)

I'm puzzled why this is failing on our CI server but works locally:

((fn [{:keys [cron]} {:keys [id]}]
                                                                (format "%s %s"
                                                                        id
                                                                        (.URLEncoder/encode  ^String (:timezone cron)  java.nio.charset.StandardCharsets/UTF_8)))
                                                              {:cron {:timezone  "Europe/Bratislava"}}
                                                              {:id 1})

;; on my computer (Mac OS)
;;=> "1 Europe%2FBratislava"

;; on the CI server (Linux)
;; Execution error (ClassCastException) at user/eval1458$fn (REPL:19).
;; sun.nio.cs.UTF_8 cannot be cast to java.lang.String

What's the way these days to comment on tickets in the Clojure JIRA? I've created an Atlassian account, but it's denying me access, and I'm not sure how to proceed.

http://ask.clojure.org

All the Jiras are mirrored there, and you can comment on them and upvote

That's also where you can create new issues, and if approved, an admin will create a corresponding Jira for it

https://clojure.org/community/contributing#_reporting_problems_and_requesting_enhancements

we are trying to reserve our (limited) jira accounts to those working on patches

Thanks!

but if you have a CA and are doing so, happy to make an account

Not yet, just wanted to chip in on DXML-52

https://ask.clojure.org/index.php/7102/transforming-fragments-non-namespaced-into-default-xmlns is the ask equivalent

is there a way to bit shift right a byte?

seems that it results in a long value

@roklenarcic no clojure function returns a byte directly, for integral types they all return longs

you can use interop, and with the right hinting etc. they can stay unboxed even, but it's not going to be the easy path

You can then call byte , I think returning a java.lang.Byte object, perhaps? Not sure whether that achieves your goal or not.

of course nothing prevents you from converting

(cmd)user=> (byte (bit-shift-right 8 2))
2
(ins)user=> (type *1)
java.lang.Byte

the problem is that I’m bit shifting a negative value

also, if you are doing this with one byte, often the real task is over a large number of bytes that get handled in various ways - check out ByteBuffer for arbitrary parsing of arbitrary offsets of that array, and the byte-streams library https://github.com/ztellman/byte-streams

so I get a massive long which will probably convert to 0xff byte?

depends upon the long value, and how you convert to a byte. Some ways of converting to a byte simply keep the least significant 8 bits and discard the most significant bits, so would not always convert to 0xff byte

Clojure 1.10.1
user=> (bit-shift-left Long/MAX_VALUE 8)
-256
user=> (byte (bit-shift-left Long/MAX_VALUE 8))
Execution error (IllegalArgumentException) at user/eval3 (REPL:1).
Value out of range for byte: -256
user=> (unchecked-byte (bit-shift-left Long/MAX_VALUE 8))
0

seems to work ok. dunno how good an idea it is though

user=> (byte (bit-shift-right 2r10000001 1))
64

why would that be an issue? it looks like the expected usage of bit-shift-right to me

not saying it's an issue, saying it seems like it would work fine

Does anyone know when a future releases the thread that’s backing it? Is it once its Callable returns some result, or after the first time someone derefs it? (assuming of course that it wasn’t cancelled for some reason)

It seems like ideally after the Callable finishes executing… but maybe that’s up to the executor vs. the future itself?

the thread is released as soon as the callable exits - it goes back into the pool in the clojure.core/future case

it is up to the executor, but I have never seen an executor that did it any other way

Yeah, that makes sense to me.

Just sanity-checking myself

thanks 👍

you can double check with jstack or Ctrl-\ to see what's really running

technically it is an ExecutorService, Executor doesn't actually have methods that return futures

Executor is a pretty great interface

> technically it is an ExecutorService true

> Executor is a pretty great interface There is always beauty in simplicity

Hi, I have a small app that makes a few Rest API calls, through which it obtains an IP address. I'd then like to exec an ssh command, replacing my current process. What's the best way to do that? clojure.java.shell seems to run a subprocess and tries to wait, so my little app just appears to hang.

right, clojure.java.shell turns the output of a command into a string, so can't really do interactive

but you can use ProcessBuilder to make a Process, and use the inheritIO method to let a terminal user interact with the resulting application

this won't make the vm exit though - it just hands the terminal over to the child

you can't do the "replace the process" bit. the jvm doesn't provide the Posix exec call

there's a one liner I've got somewhere, I can even exec vim, edit a file, then exit back to a repl

the gotcha is you have to make the shell (which is reading form the same terminal) wait for the process to exit

@noisesmith, that sounds like a good workaround. Can you share the one-liner?

grabbing it now

@eamonn.sullivan

user=> (-> (ProcessBuilder. ["nvim"]) (.inheritIO) (.start) (.waitFor))
0

that 0 is the exit code of neovim

you can of course add more args to that vector, or run /bin/sh if you need redirects etc.

the waitFor prevents the editor and the repl from fighting over the same characters on input

Awesome, thank you very much!

you can even continue to run other things in other threads while that executes (of course you probably want to make sure they aren't reading or writing stdio)

another option I guess would be to ask the system to launch a new terminal application with the built up ssh command as its initial command. xterm -e ssh X.X.X.X or what have you

yeah, that's windowing system / ui specific though, where the processbuilder just relies on stdio being connected to any terminal

eg. it works inside tmux while sshd'd from another host

true. I'm still kind of amazed that your PB trick works. but it certainly does

it's all files, right?

or you could just write an ed clone inside of clojure

haha right - original usage was ssh, vim is "feature complete" for tty I figured

I guess. I just kind of assumed that when java says "inheritIO" it means inherit java streams for IO. not low level pass over the fd's. anyway it's cool

"The fundamental unit of information in Clojure is data." https://medium.com/@lwhorton/why-clojure-script-e4a69cc5168a So, is that different in other languages? How?