Hey friends, what are the performance characteristics of swap! ? I have a program that stores a bunch of state in a single atom, (roughly 30 kb of data once exported to json, but that should grow substantially as the simulation becomes more complex) and calls swap! on that atom a minimum of once per frame, which is roughly 20 times a second. I wonder partly because I seem to have a pretty bad memory leak, I haven't had time to really search it out yet but I thought I would check if my whole premise was an issue before I search too hard profiling indicates that it comes from the hottest loops, which is where the global atom is being processed and swapped. Thanks!

Have you tried benchmarking (swap! your-atom your-change-fn) vs (your-change-fn some-data)? I'd suspect your-change-fn might be a major contributor.

I haven't yet! The profiling made it look like swap was the hotspot and I didn't find any information on if it was ok to run swap dozens of times a second, this narrows my search a lot!

Hi everyone. Is there any way to convey a dynamic var's binding into the body of a list comprehension without using another var?

user=> (def ^:dynamic *foo* 0)
#'user/*foo*
user=> (binding [*foo* 1]  *foo*)
1
user=> (binding [*foo* 1] (for [n [1]] *foo*))
(0)
user=> (binding [*foo* 1] (let [p *foo*] (for [n [1]] p)))
(1)

(binding [*foo* 1] (doall (for [n [1]] *foo*)))

The issue here is that the lazy collection returned by for is realized only outside of the binding.

aaaah riiight

yes yes

thanks @p-himik !

What is the fastest way to reset the REPL to the state when it is freshly runed? I want be sure all ns are unloaded and I don’t want to lose time for reset REPL each time to be sure if dependencies are correctly reduced.

@kwladyka are you familiar with https://github.com/weavejester/reloaded.repl?

@borkdude I don’t think this is what I need. Does it demand Sierra component? Also the issue is not reloading, but unloading in this case.

I remove dependency from ns dependencies and reload ns. It works. But if I kill REPL and load ns then not.

ok I found manually which dependency make the issue, but anyway I am interested in how to reset the REPL without kill and run again

you probably want https://github.com/clojure/tools.namespace

But first, it will unload (remove) the namespaces that changed to clear out any old definitions.

which i think is what you want

Hmm it could work. I have to try. Thanks.

What does one typically do when your deps.edn includes dependencies that have transitive dependencies that are only available in 3rd party Maven repositories? Is deps expected to be able to handle this case?

@mac01021 there is a :mvn/repos option in the deps.edn

you should add the repository there

Does anyone here uses postal for sending email by SMTP?

What libraries are people using for testing http calls?

we use postal to create messages but just use javax.mail to send it

My doubt it was i was able to send a attachment by a inputstream

Because i saw that i can send with http://java.io.File

I was using Postal in the past, but I don’t remember too much

I haven't use .File with postal, but my experience with the jvm generally is that people often assume they need a File when really they could use something more abstract, or not reliant on using a fileystem

eg. io/resource to read from inside a jar, or ByteArrayInputStream to read directly from bytes in memory

I think postal shells out so it may actually need a file

If I remember postal has :attachments key in map so you can set paths to files.

I didn’t use any other method

oh actually it is not a path ,but http://java.io.File so probably you can use stream too

Remember that (+ [1 2 3]) is erroneous - I wonder why (max [1 2 3]) is not - the result is [1 2 3] even though no ordering of vectors is defined: (max [1 2 3] [4 5 6]) is erroneous as well. I think it would have made more sense to return an error for (max [1 2 3])?

@jakob.riishede.moller many clojure functions return identity for a single arg without consuming it or checking its validity in any way

user=> (conj :a)
:a

this is useful for cases where you would reduce across an input collection and need a sensible base case

Is [1 2 3] a sensible base case for a function that computes the maximum?

identity is

and identity of [1 2 3] is [1 2 3]

it works accidentally, whether clojure should eagerly reject invalid inputs is a ship that has sailed already

Well, if at least there was consistency, so that (+ [1 2 3]) returned [1 2 3]?

I agree that the inconsistency is annoying, I doubt there's an easy way out. That said I find clojure generally more consistent than most languages I've used.

Pragmatically, I think it's better to avoid invalid inputs (knowing you can't count on being saved from them by the compiler or the runtime). I have my own pet peeves (eg. merge accidentally working, sometimes, on things that are not hash-maps)

or (Math/PI) working in the place of Math/PI (despite not being an invocation)

Well - thank you @noisesmith - at least: now i know 👍

Are there any libs or examples of neat ways of interacting with nav-able structures at a REPL

REBL works with Cognitect's AWS lib, dirs/files, data for charting, Java class hierarchies, jdbc data, etc

@lilactown next.jdbc produces datafyable/`nav`able result sets by default from execute! and execute-one!

I wasn’t clear enough. I am not looking for examples of datafy and nav, and I know about REBL. I’m wondering if anyone has explored a more ergonomic way of interacting with datafy/nav directly at a REPL. Sort of like https://github.com/eggsyntax/datawalk

(preferably that you could evaluate in a buffer though, so datawalk doesn’t fit exactly what I’d like)

I guess the “semi-interactive” version of datawalk is basically what I’m thinking of

omg I'm dying waiting for that datawalk gif to load

you can totally make something like datawalk for nav, but then you'd be re-building REBL @lilactown

yeah it takes forever

I understand. the tradeoffs I’m thinking about for REBL are:

• doesn’t work in CLJS (which is where I actually want to use this right now) • have to leave my editor to use it

for my use case, there’s already a purpose built set of devtools for visualizing the objects I want to datafy and nav and I’m interested in building some utilities to interact with them at the REPL

I was hoping I could implement some wrappers around it with datafy + nav and call it a day 😉 but looks like I’d have to build it myself anyway

i think @thheller is cooking something exciting up along these lines

datawalk doesn't seem work in nREPL, womp womp

thheller’s inspector looks awesome but, again, there is already an excellent external devtool for inspecting this data; I specifically want something that works at a REPL. I have my answer, which is, this does not exist yet as far as we know 😄

I don't think you can get very far if you constrain yourself to a text interface

^

as long as you can assume no background thread is trying to print, you could have a curses UI inspector

not sure if it would be worth the trouble to implement...

oh, there is a guide: https://clojure.org/guides/repl/data_visualization_at_the_repl

There are certain use cases that are better at a REPL imo

I'm trying look at the current state and props of a react component instance without leaving my editor

It's simply walking the react fiber tree and finding where the element type equals the component I want to inspect

But react fibers are opaque data (to CLJS) so I thought I could buy myself some time and effort and use datafy/nav. But datafy/nav is too raw to really be usable at the REPL for that

sounds like you just want tree-seq and filter

navigating is such a low level thing, don't do it, be lazy, search

This code:

(defn- grant->pin [grant]
  {:id (:id grant)
   :amount_recommended (:amount_recommended grant)
   :organization_name (:name grant)})

(defn aggregate-pin-data [data]
  (-> data
      (get-in [:records :grant_request])
      #(map grant->pin %)))

class clojure.lang.Symbol cannot be cast to class clojure.lang.IPersistentVector (clojure.lang.Symbol and clojure.lang.IPersistentVector are in unnamed module of loader 'app')

(defn aggregate-pin-data [data]
  (-> data
      (get-in [:records :grant_request])
      (#(map grant->pin %))))

try this ☝️

that works!

I could've sworn I've passed lambdas like that to -> , does this not work at all? Or only in specific cases?

It shouldn't work

@ctamayo it helps to look at the macroexpansion of the -> form

zacly

@noisesmith I should've thought of that 😛

thanks

user=> (macroexpand '(-> x #(+ % %)))
(fn* x [p1__224#] (+ p1__224# p1__224#))

notice how x becomes the name of the fn, and doesn't appear in the body at all

don't try to fit everything into a -> chain

it's not like a Street Fighter combo

lol

here's how the (()) hack fixed it:

user=> (macroexpand '(-> x (#(+ % %))))
((fn* [p1__228#] (+ p1__228# p1__228#)) x)

->->><?as->cond->!

haaadouken

that'll finish him.

anyway, the (#(,,,)) hack definitely feels gross...what's the suggested style?

The simplest: extract a function

it took me a while to get that to be honest

use a let, or arguably (-> x (f y) (->> (map g))) but even this is controversial

->> / as-> etc. are intentionally designed so that they can nest inside -> fwiw, but opinions about actually doing so are mixed

(->->><?as->cond->! x
 :-> (f y)
 :->> (map g))

OK poe's law definitely got me on that one

I'm gonna go with "yikes"

Without threading it's pretty simple.

(defn aggregate-pin-data [data]
    (map grant->pin
      (get-in [:records :grant_request] data)))

if you're not using randomcorp's thread-first-thread-last-backwards-question-mark-as-arrow-cond-arrow-bang, you're missing out: https://github.com/randomcorp/thread-first-thread-last-backwards-question-mark-as-arrow-cond-arrow-bang Also check out the video: https://youtu.be/jlPaby7suOc?t=699

Thanks for the much-needed reminder. I've literally seen every clojure talk ever....But I guess I still haven't learned my lesson because I'm not modeling this in XML.