What strategies, if any, do people use to decouple sub systems within an application. For example decoupling a database access layer. I've been using protocols to group common functions and passing the instances down into subsystems using stuartsierra/component. I can also see people using weavejester/integrant and mapping single functions. I can also see directly coupling/referencing subsystems and segregating them in separate namespaces.

I have a project where starting a REPL with Java 1.8.0_192 takes 11 seconds and with Java 1.8.0_201 takes 44 seconds. I'm wondering if this is a known issue or something idiosyncratic to my project.

Looks like the Clojure portion ^ is easy to repro with a fresh React Native project; will check in #cljsrn

Hello

Looking for jdbc that uses threadpool

Hi all, I'm new to Clojure I'm new to Java. 🙂 Can anyone point me to the right direction? I'm trying to serialize an https://github.com/thi-ng/ndarray

How do I apply a function (defn myfn [& {:keys [a b]}] ...) to a map m (`{:a 1 :b 2}`)?

$ clj
Clojure 1.10.0
user=> (def m {:a 1 :b 2})
#'user/m
user=> (defn myfn [{:keys [a b]}] [a b])
#'user/myfn
user=> (myfn m)
[1 2]

Sorry, I meant: (defn myfn [& {:keys [a b]}] ...)

then you probably need mapply

it’s a function that’s not in clojure, but in several helper libs:

(defn mapply
  "Applies a function f to the argument list formed by concatenating
  everything but the last element of args with the last element of
  args.  This is useful for applying a function that accepts keyword
  arguments to a map."
  [f & args]
  (apply f (apply concat (butlast args) (last args))))

noticed functions like assoc and contains? operate on vectors (by position), but dissoc throws an error. Seems like this should work as a complement to the aforementioned functions - no? Or is this an intentional omission for performance reasons?

what would (dissoc [:a :b] 0) mean?

removing something from the middle of a vector isn't a simple operation, so it isn't built in

remove item at position 0?

also if you find yourself wanting to do that, you should probably use a different datatype (eg. finger tree)

the result would have an item at position 0

(contains? (dissoc [:a :b] 0) 0) would be true

good points 🙂

along with the non-constant performance of dissoc there

i hadn't realized that until you asked it so i like your question 🙂

yeah I figured the performance would make it bad, just curious on the reasoning.- thx

you have keep-indexed tho (keep-indexed (fn [k v] (when (not= k 0) v)) [:a :b :c :d])

see also the inability to check something sequential for a specific value (what people often naively think contains? would do) - it's possible, but there's no simple built in because doing so often indicates you should be using a different datatype

for what it’s worth I was building a custom version of assoc that wouldn’t add nil values in order to reduce gc overhead (relative to pruning). it works as I expected, but in doing so I stumbled upon the issue. edit: note that I’m not even using vectors, but I was attempting to achieve feature parity… so it was really just a question.

@noisesmith wouldn't something like some count as a built in for that?

so it’s not a data type issue

i think he means without doing a linear scan

@lockdown- yes we have functions that do linear scans of collections, but nothing that specifically checks membership of a given value

got it

Hi, does anyone have recommendations on how to get the length of a video in clojure... Sadly I must use windows.

i was using ffmpeg on a mac, and calling it with processBuilder, however I'm running into issues getting any output at all while using CMD instead of bash

I tried loading the file as a media object using ffmpeg, but ffmpeg doesn't support MOV files .

@jdkealy you should be able to pipe output between processes via InputStream and OutputStream, if all the executables are present

java does have multimedia libraries, that's the next thing I would look for

even if there was a clojure binding, using the lib via interop is likely a better choice

right! https://gist.github.com/jdkealy/65edec6c28a89f378c27803fb78be6d8 so this calls bash, would you know how to do this in windows ? I know you can call bash via CMD, eg. "CMD" "C/" "bash" but the stream just returns ""

or... if slurp is returning "", is there a silent error somewhere?

I would look for a specific library in Java/Clojure before piping stuff to bash/cmd

ffmpeg writes a lot of things to stderr rather than stdout, afaik @jdkealy