someone familiar with boot and can please explain me how to make use of java imports within a task?

those calls are weird and interop forms don't work that way

get rid of the binding of drv-mgr and use DriverManager everywhere where you currently have drv-mgr

the import form ensures that DriverManager will work without needing anything like resolve or the full package name

same thing with initializer - use SQLAccessControlSystemInitializer instead

@wottis see this example

+user=> (. Character isUpperCase \A)
true
+user=> (def c Character)
#'user/c
+user=> (. c isUpperCase \A)
IllegalArgumentException No matching method found: isUpperCase for class java.lang.Class  clojure.lang.Reflector.invokeMatchingMethod (Reflector.java:53)

the . form breaks if you don't use the class itself to get the static field - you'd need a different syntax (maybe even reflection?)

@noisesmith unfortunately just using DriverManager doesn't work. It complains that there's no such thing 😕

https://github.com/boot-clj/boot/wiki/Run-time-requires-%28within-task-definitions%29

don't know if that also affects imports

but i certainly can't just do an import 😕

if DriverManager is not on the classpath, none of that code works

the issue is that you need the right classes on your classpath when that code runs

yes - resolve works for vars, but not for classes (as far as I know at least...)

maybe you want (Class/forName "java.sql.DriverManager") - that's the equivalent of what resolve does for vars

oh - the same error for no matching method happens with Class/forName

yup

I can't find in the docs any way to call a static method on a class not available until runtime, except using clojure.reflect which is not exactly a simple or pleasant way to do things

thanks alot

a lot

sorry I couldn't be more helpful - there are various libs for reflection if you look, but I bet there is a smarter way to do this in boot, for example ensuring that your code is loaded, compiled, and run in a context where the classpath has all your deps on it already

but I don't know boot, I'll let someone else chime in on that

learned something knew and gained a better picture. that is very helpful ^^

general question about everyones workflow... sometimes i'm working in a new project in core.clj, and get interrupted... and then at some point come back to my repl and attempt to restart. My repl won't restart, because i didn't find a good stopping point. Should i be doing my development always in core_test.clj, or is there some wayto have a worksheet or something? I'm using emacs + cider. any tips appreciated.

just wondering how folks do this sort of thing with a repl driven workflow. It's fun, but when my phone rings and i lose track of thought, i find i have to trace my steps back for a while to figure out what i was doing.

that's why I don't like the :init-ns option actually - if you don't use that, you can always get a repl in user and then fix your file until (require 'my.ns :reload) succeeds (then switch to that namespace)

a workaround is to (comment ...) the whole body of the ns, then start a repl, then take things out of the comment bit by bit, fixing as you go

ok, let me read up on :init-ns, thanks. I'm sure it's somehting in project.clj i overlooked.

it's usually in there by default, yeah

I want to learn Alan Kay style OO programming, without using smalltalk. Are there any good books/tutorials on doing Alan Kay style OO programming in Clojure ?

not to be pesky, but i just googled this, and am curious why you're interested in this? It sounds like the opposite of all the great things i like about fp.

i was just reading part of that and in my brain doing a s/object/list/g but what do i know

Hmm, Rich Hickey in https://clojure.org/about/state#actors explicitly states why he decided against the Actor Model 😞

@joefromct : the original "OO programming" is much closer to Erlang than to Ruby/C++

in that regards, it's "very pure"

heh, interesting stuff. hadn't thought of this. I think this was funny: > [actor model] is a world in which everyone sits in a windowless room and communicates only by mail

I kinda like that.

It enforces encapsulation / API.

And separation of concerns.

enforces or forces? I guess if you know beforehand an api is maybe needed then you have the option, but i guess not-having-an-api is sometimes a worthy trade off

it also means you can't separate data from the stateful protocols of message transfer

I don't now what these words mean, but I do feel like erlang workswell in practice.

One of the benefits of fp is transparent access to data. Forcing data hiding means adding a layer of complexity to anything that needs the data.

yeah, but the real world doesn't mirror FP -- i.e. I can't read your emails / bank balance

"within each actor, I like the idea of FP" -- bue between objects, I like this idea of well desinged messaging

I don’t see why you need objects. I find types are more useful than objects.

let's move this to #off-topic 🙂

however, if anyone has a nice way of doing actors in clojure/cljs, please let me know 🙂

Copying the real world is overrated. Modeling it well is another concern, but making data less accessible is often just a crutch to make mutation less problematic.

I'd rather global mutable state than hidden mutable state even.

I saw a library somewhere but never used it. TBH, if I wanted to use actors, I would use Akka for that instead of trying to do it in clojure.

Actor model is like a capitalistic market. Clojure's top down control is like a totaltarian government.

This breaks on reloading via tools.namespace - I get a ClassCastException for callsites to calculate that whatever implementing class I pass cannot be cast to IObjective

Without the :inline function the reloading works as expected. What is the reason that it does not when inlining. Note: all code is in the same namespace.

ok, it's not the :inline implementation but the type hint on the first argument....

a tangential question here, where would I find documentation for the :inline metadata in the above?

I dont think there is any. It's not really considered a public feature

Hi folks, can you share (via gist) your profiles.clj, I'm looking for examples of using "pimp my repl" tools like inject, debug-repl, push, try etc

I know that vinsaya was moved to lucid

@alexmiller the ClassCastException still arises without :inline implementation if the first argument has the interface type hint. do you know why that is?

high level question, in a previous life I used to write some groovy code and one really nice feature of the language (and yes, feel free to bash good old groovy) was power assertions:

assert [[1,2,3,3,3,3,4]].first().unique() == [1,2,3]

// Output:
//
// Assertion failed:
// assert [[1,2,3,3,3,3,4]].first().unique() == [1,2,3]
//                          |       |        |
//                          |       |        false
//                          |       [1, 2, 3, 4]
//                          [1, 2, 3, 4]           

for complex expressions I found the explicit visualization extremely helpful. I know Peter Niederwieser implemented this for scala as https://github.com/pniederw/expecty

What libraries would you use to implement video streaming in a Clojure web project?

@mbjarland that's pretty nice, I'll try to bash groovy a little less now because of that 🙂

@mpenet I haven't been able to get basic auth working in spandex client usage. is it necessary to set :request {:authentication? true}? (i tried)

you're using`:basic-auth {:user "..." :password "..."}` ?

yeah

confirmed it works if i bake in an Authorization header (base64 encoded) instead

(es/request
    (es/client
      {:hosts hosts
       :http-client {:basic-auth {:user user :password password}}})
    {:url (es-utils/url [index-name])
     :method :head})

(does not work)

response 403 nil body

to use spark + clojure; do I have to install spark separately, or can I pull in spark as a boot/lein dependency ?

Can you create a ticket for this?

sure

where can i get javadocs for clojure ? and how can i set it up with cider emacs ? thanks for any help

@ashishnegi Javadocs, or http://clojuredocs.org ?

clojure question, is there a shorter way of adding a value to a vector in a map optionally adding an empty vector if there was no vector there, i.e.:

(defn shorten-this [data new-entry]
  (let [entries (get-in data [:consultant :entries] [])]
    (assoc-in data [:consultant :entries] (conj entries new-entry))))

-- repl
(shorten-this {:consultant {:entries [1]}} 2)
=> {:consultant {:entries [1 2]}}

@lsenjov i want to use to jump from emacs to source code locally..

(partial update m (fnil conj []))

I can't help you I'm afraid, I'm using vim-fireplace

er, sorry

But there should be a shortcut for viewing source with the emacs repl

@donaldball : ) ok, that is indeed shorter, will look into it

(update-in m path (fnil conj []) value)

something like that 🙂

@lsenjov There is.

Well, there is with CIDER.

@lsenjov so, can you tell from where you got java source code ? did you just git clone clojure.git ?

I don't think you're wanting the java source code unless you're doing clojure development (tell me if you are)

Otherwise you want the docstrings of functions

Is there a particular reason you're wanting the java source itself?

@dominicm my eamcs is setup with cider and it works good for clojure code.. but everytime i am at : ThreadPoolExecutor i can't find the java code file.

@lsenjov just want to go down rabbit hole..

@ashishnegi it doesn't work for java code.

You'll need to look at the source externally

@donaldball ahhh...fnil, I have a new friend

Or look at other emacs plugins which might offer this functionality

@mbjarland with specter (setval [:consultant :entries END] [2] {:consultant {:entries [1]}})

Is there a quick way to refactor out a block of utility fns into their own ns? (using cider, clj-refactor, emacs... the usual 😉 )

@josh.freckleton You mean move a function to another ns or do you mean extract out some code into a fn?

sorry, move a function to another ns (or preferably a whole block of fns)

(ie highlight a few functions in my-ns, and move them to my-ns.utils, but referenced appropriately still in my-ns)

@josh.freckleton https://github.com/clojure-emacs/clj-refactor.el/wiki is the list ftr.

do they need to be in a separate ns or just a separate file?

@josh.freckleton https://github.com/clojure-emacs/clj-refactor.el/wiki/cljr-move-form ?

@mobileink well, both, right? is it possible to have a separate file with the same ns? I never even thought of that... @dominicm I think that's it, thanks!

@josh.freckleton it is actually, clojure.core uses this to split up core.

I was surprised too!

you can use load (if i recall). see the clojure.core source for example.

@josh.freckleton it's possible to do that, not sure that I recommend it.

interesting, huh, I'll have to keep an eye out for when that might come in handy!

Without the "separate files" thing clojure.core would be much larger than the 10k lines it already is.

I'd think that in most cases you could find some abstraction to divide things along, and come up with a fitting ns name

It also has the nasty habit of breaking a fair amount of tools.

works great if you need to generate clojure source from config files and add it to an ns.

so, can you have multiple ns's in the same file?

what are you trying to solve?

nothing with that, the question just follows from the previous discussion

just my curioisity!

ah.

@josh.freckleton yes, multiple ns'es in the same file can be done, but the ones that don't match the filename won't work properly with require

and as always, will break tooling, confuse users, etc.

well you learn something new everyday with clojure!

yeah, i think CIDER makes the assumption of ns = file

as does tools.namespace, and Clojurescript as well (IIRC)

@tbaldridge I suppose there's no particularly good solution to the code organization vs api exposure problem then? I know you're not a fan of potemkin also.

Personally I'm in favor of the model used by core.async and a few other libs:

public API in one namespace, which are mostly wrapper functions around functions in other namespaces

example: https://github.com/halgari/odin/blob/master/src/com/tbaldridge/odin.clj

also: https://github.com/clojure/core.async/blob/master/src/main/clojure/clojure/core/async.clj#L50-L72

@tbaldridge that's a good architecture I've found. Often, there are mini apis within one api that can be broken down similarly within a project too.

you might find core.matrix instructive. one api ns, with the ability to switch to different implementations dynamically.

is there a better way than top to determine if jvm-opts memory settings are being respected?

jstat

lots of flags there... -gc -gcutil

thanks!

is there a good way to map across a seq but with the function calls rate-limited?

for example, let’s say a the map function contains an http request

thinking something related to transducers but I’m having trouble formulating it

hello everyone I'm fairly new to clojure and reading the .spec docs ive encountered double colon keywords like ::wtf-is-going-on are they special in some way?

@plins yes, it’s a shortcut for the current namespace

https://clojuredocs.org/clojure.core/keyword#example-542692d3c026201cdc326fe0

@plins and ::foo/bar will resolve foo in the current namespace. So:

(ns user
  (:require [some.lib.foo :as foo]))

::foo/bar
; => :some.lib.foo/bar

thank you folks

how can i check to see if a record implement a specific protocol or not ?

any compact way to group-by a vector of vectors on nth element while also removing the grouping element from the result?

@mbjarland can you give an example of input and output desired?

@lxsameer try clojure.core/satisfies?

@brycecovert

(group-by first [[:a 1] [:b 2] [:a 3]])
=> {:a [[:a 1] [:a 3]], :b [[:b 2]]}

seeing as how I am already using specter I can get this done using that, but figured there might be a pure clojure way

@tbaldridge thanks man

@mbjarland Others might have more ideas, but in cases like this, I prefer to simply use reduce.

@brycecovert ok, thanks

(reduce (fn [m t] (update m (first t) conj (second t))) {} [[:a 1] [:b 2] [:a 3]])

@mbjarland I think it's fairly compact even without specter

;; With a (badly named) function
  (defn group-by-by [f g coll]
    (reduce (fn [acc x]
              (update acc (f x) (fnil conj []) (g x)))
            {} coll))

  (group-by-by first second [[:a 1] [:b 2] [:a 3]])

  ;;Inline (brycecovert forgot the fnil to make vectors instead of lists)
  (reduce (fn [acc x]
            (update acc (first x) (fnil conj []) (second x)))
          {} [[:a 1] [:b 2] [:a 3]])

oh wait, it’s wrong

Personally I like my first approach better, but here’s an idea:

(apply merge-with into (map (fn [[k v]] {k [v]})  [[:a 1] [:b 2] [:a 3]]))