I have a database connection pool I am messing around with in the REPL. Is there any sort of sophisticated way to view active resources such as a database connection pool or open files, etc etc, beyond inspecting things namespace by namespace? I'm finding keeping track of what is in the REPL quite difficult.

You could use something like Integrant to orchestrate each and their dependencies. Then you can initialize and destroy them as you like. I'm sure there's a “check state” function

https://github.com/weavejester/integrant

From the looks of it, it might store the state of the of each component on metadata of the config map

https://clojuredocs.org/clojure.core/meta

I’d rather choose a proper component management library, e.g. integrant, mount, component or clip, instead of just storing the component state in metadata :thinking_face:

the concept of https://github.com/weavejester/integrant is interesting and worth take a look, instead of just an service component management tool, it can be used as a general dependency injection micro-framework

Right. I'd use Integrant as well. I was just describing how it works internally

Integrant places metadata on the config map

so for loops aren’t actually loops?

they are just kind of ways of making sequences programatically?

and it stores the output of each iteration of the loop in the output sequence

If you want loops, try https://clojuredocs.org/clojure.core/loop/https://clojuredocs.org/clojure.core/recur

I don’t quite understand the placement effects of :while and :when

like always at the end makes sense

in the middle is not clear what its doing

doseq is closer to your standard "for-each" loop

it only applies to the variable immediately preceding it?

but loop combined with recur is your general purpose tool

that’s why https://clojuredocs.org/clojure.core/for stated that, it is list comprehension

and it always return a list, even an empty one if nothing to comprehend

for [x (range 3) :when (> x 2) y (range 3) :when (< y 1) ]

kind of same as

(for [a (range 10)] (inc a)) = (map (fn [a] (inc a)) (range 10))

for(int x = 0; x < 3; ++x) if(x > 2) for(int y = 0; y < 3; ++y) if(y < 1) { do something}

(coming from C/C++ here)

if the do something is "add it to a collection", then yes

right

but with the caveat that for is lazy

so if you do this

docs don’t say its lazy

you sure?

https://clojuredocs.org/clojure.core/for

(def stuff (for [a (range 100)]
             (do (println "abc")
                 a))))

you don't know how many times that println will be called

it will be called all 100 once you "realize" the full sequence

(for [a (range 10) b (range 11)] (+ a b)) = (mapcat (fn [a] (map (fn [b] (+ a b)) (range 11))) (range 10))

yeah I understand if its lazy

but clojure's lazy sequences are "chunked"

but docs don’t say lazy

>

and yields a lazy sequence of evaluations of expr.

I would avoid drawing any equivalency between a for loop and a for list comprehension

oh damn

ok

sorry

in the middle there

yeah its in a dense space so its easy to miss i guess

hmmm

its purpose is different than a C/C++ for. Its just for transforming a sequence of data and getting a new sequence out.

A list comprehension is a basically a dsl for composing list processing operations (map, mapcat, filter, etc) to build a new list from some given lists

Similar to set builder notation in math

un`for`tunate naming to be sure

yeah, it probably should have a better name than for

but, its way too late for that

ship sailed a long time ago

The key thing to understand with for, is the order of clauses in the dsl determines how they would be nested when but from map, filter, and mapcat

And nesting determines variable scope

sure, just like let

I just have to re-implement this functionality in C so I’m trying to understand it completely

https://github.com/Zelex/jo_lisp

If you have implementations of map, filter, and mapcat the easiest thing is to have the for macro expand into those calls

don’t think I did mapcat yet, but the others I have

working my way through the spec

I first read the for description and I was like… yeah I’m gonna do this later. And here we are

lol

can you do

(for (x (range 3)) :when (> x 1) :when (> x 2) (y (range 3))

This readme is, I dunno, it is important to swing for the fences I guess

?

basically double when?

or combining when while etc

Each when is like wrapping in a call to filter

ok

so its arbitrary

While is like wrapping in a call to take-while

I dunno what you mean by arbitrary

as many as you want of whatever you want and in any order

:let :when :let :when :while

etc

not that anybody should actually do that

but if the language supports it…

For doesn't allow :when, :let, or :while before the fist sequence binding

ok

thats good to know

I thinking writing your own lisp is a great project, and looking at clojure for inspiration while doing it is great, but saying it is clojure when you don't know clojure might not be a the best plan

I’m an experienced coder of many languages, this is my first interaction with clojure of course

http://jonolick.com

I’m trying to be careful, but yes, great testing is required

https://www.clojure.org/about/rationale is good reading

I found that I made a lot more progress after I stopped trying to find analogous constructs from other languages

If you are going to claim to be faster then clojure on the jvm, then I think you need to be clear about what your benchmarks are. And I would be shocked if you are new to clojure if you are benchmark it well. But even what "well" means can be debated(start up performance, before jit after jit, jit agnostic, etc)

of course, I’m not claiming (yet) thats its faster in every case

it is faster though in some cases

though the implementation is incomplete, so who knows if that will still be a 2x perf gain vs JVM when I’m done

to be clear, I never expected it to be faster than JVM, but it turns out it is

I just wanted it to be comparable in simple cases

as I got to optimizing though, its much faster in some cases

but don’t take my word for it, and don’t measure it until its more complete 🙂

when it gets further along I’ll benchmark it more properly

Like, as a beginner, maybe you are just typing stuff in the repl, benchmarking the special cases interpreter clojure uses for simple forms in the repl, when most complex clojure programs are compiled to jvm bytecode and then fed to the jvm and then host loops are chewed through by the jit

right, which is why I was surprised that it was faster

it shouldn’t be

unless JVM is just optimizing poorly the code

Like I said, depending on what you are testing, you may just be testing in a way that is slow

And being a beginner you don't know that, and don't give any details of your benchmarking in the readme

really I just want an embeddable clojure

thats the real goal

and fast enough to be able to do real things

we will see where it ends up

its very early days for it

Sure, but I suspect you would be happier with something like sbcl

This is a single file library 🙂

or will be

🙂

its the simplest embeddable method

That is unlikely to be clojure

watch me 😉

if I fail, then I’ll fail in blazing glory

also, I really don’t like the JVM

or Java in general

I mean, I've been hanging out in various clojure channels since the early days, I've watched lots

which is why I’m like “hells no” to that

and no, graaal VM or none of that

Yeah, which is why I suggested you look at sbcl

you don’t need to do anything nearly as complicated

people are over engineering it imo

Steel bear common lisp

Or ecl (embeddable common lisp)

@zelexi - quick question. You’ve about 3000 lines of code, but I don’t see any tests. How do you detect/handle any regression? It looks like you’ve implemented persistent vectors and bi directional persistent vectors too. How do you verify expected behaviour?

Thats on the TODO, and if there is a good set of test programs to run which do that, please point it out

Clojure was designed to run hosted on some platform, as the rationale mentions

I mean, as of now, you’ve benchmarked, but how are you so sure that what you are benchmarking works to begin with?

I just started this like a couple weeks ago or so

so its all baby infancy right now

I’m just trying to get my footing in the right place

test.clj tests for correctness

test2, test3 also test other stuff

not every test was saved

but its not well organized at the moment

I also use it at work for real things

so it does get some actual usage

There are no tests at all for any of the vectors stuff

thats cause vectors aren’t implemented yet

at least, not at the clojure level

I have written up the C++ code to do it

and MAPS use vectors as the underlying type

Why not test the C++ code itself? I mean, testing your interpreter for correctness is one thing, but there’s so much code out there, that it might make sense to write at least a few unit tests maybe? At least that’s how I feel like I have a grip on things

I do

I have tests for that

but its commented out

not run unless I want to test

I don’t think its ready for real-world tests yet

its just not complete yet

why not stick a target in your Makefile and make it repeatable instead of commenting out some where?

somebody else wrote the makefile

I didn’t

was just a day ago or so

but anyways 🙂

Oh, I missed the link to jo_lisp. Nice. I mentioned in a thread that this sort of thing https://ferret-lang.org/#outline-container-sec-2, but I'm almost thinking I shouldn't say so, since I think that it's always worthwhile trying these things again. After all, it's always a valuable learning exercise, and anyone can potentially come up with ideas that other people haven't had before!

yes, there’s lots to do

it has been invaluable to me in learning the language

I have to explore every nook and cranny

That’s good to hear. I would just hold off on benchmarking or saying anything public yet. The clojure community is generally quite welcoming, but you’d definitely ruffle a few feathers if you make bold claims and your Makefile is 3 days old

lol 🙂 not claiming anything other than goals at the moment

ferret-lang is cool!

great unit tests in the docs there too

https://janet-lang.org/ is by the author, and more clojure-like (and probably the most embeddable clojure-like atm - great C interop) - edit: correction - fennel === janet author - ferret is not - should have double checked before commenting (ferret seems to keep parity with clojure while janet/fennel diverge)

If you need to be in C/C++, having these options are amazing - problem with any of the C-buddy langs as an option for general computing is that it's very hard to compete with the ecosystems/momentum of the higher level languages (even if they may be less performant) - I like using janet or bb for various things since they both have fast startup, but languages are never really competing in a 1 on 1 void of lang vs lang - its always lang+ecosystem vs lang+ecosystem, and its difficult for any ecosystem to beat out npm or maven (and stack clojars/gitlibs on top)

That's fine, I'm making it for me mostly

And anybody else who wants it, but even if it's only me that finds it useful, that's good enough for me

I think that's awesome - I just caught the tail end of the conversation and the mention of ferret-lang - are you transpiling into generated c/c++, or making a VM/bytecode layer?

bytecode layer

eventually

🙂

right now I’m just trying to get the language down 100%

and tbh its great

clojure is winning me over

I want basically instant startup time

and no compiles

so it can be used in place of scripts

like replacing perl or bash etc

if you want a reference for a parser, i wrote an edn parser in rust recently

definitely!

https://github.com/bowbahdoe/edn-format

cool!

its basically just one chonky file. i don't think its impossible to translate to C if that is your chosen life path. stuff like uuids and bigints would be a thing to keep in mind

yeah, I started implementing bigints and bigfloats

seems massively inefficient use of compute tbh

64-bit is not enough for people?

yep

Also > its the simplest embeddable method If its a C/C++ codebase yes. If its anything else then the implicit "we don't have anything resembling a package manager" state of the world is no longer true

For sure :)

I work with Sean Barret (author of stb libraries) we do single file libs all the time

It's great for just plop in and go

Again though, I'm talking about C/C++

Why hate the JVM though? It's a neat runtime, in spite of its flaws.

I don't want to ruffle any religion feathers too much, sufficed to say, I don't like the JVM or java at all. It's kind of repulsive to me. I like clojure though

Yeah saying any more will just spark a debate and I don't want to debate right now lol

I know a whole industry is built around java, but it's just not my cup of tea

Hey folks, try to remember to use threads for conversations please -- especially long, rambling ones that are unlikely to be of interest to most of the nearly 15K members of this channel. Thank you. /admin

In next.jdbc. I want to get camlCase key in result map

(require '[next.jdbc.optional :as jdbc-opt])
  (defn as-caml-maps
    [rs opts]
    (jdbc-opt/as-maps rs (assoc opts :label-fn csk/->camelCase)))
  (query ds ["select * from wf_run_task limit 1"] {:builder-fn as-caml-maps})

I am practising clojure ring and I am hitting a post req and getting the value in the body as rg.eclipse.jetty.server.HttpInputOverHTTP how to retrieve the value from body? I refereed https://stackoverflow.com/questions/42829594/how-to-get-the-content-of-httpinputoverhttp-in-clojure-compojure-ring-project and added (wrap-multipart-params) handler, my body parameter from input is :body {:Studyid 45}

struggling to google this how do i do "\" if i eval that in a repl it fails which I get so I though i would do "\\" but that prints 2 slashes I get the meaning of the slash just not how to make it a single slash, hitting an issue where I have \= in a string causing me issues.

I was thinking about posting a question. Then find the answer by myself 😺. How and in which channel should I discuss such thing where I sort of have an answer?

Hey guys, how is it going?. Currently I'm reading an edn file as an exercise of my clojure training. Im using the following function which seems to find the file but not able to read and serialize the edn content

(defn read-edn-file
   "read edn file content"
  [file-path]
  (clojure.edn/read (java.io.PushbackReader. ( file-path))))

What does this represent? (repl output) #{[#:dumrat.bookkeeper{:ledger 2}]}

a set, containing a single element, a vector, which contains a single element, a map

the map is written in the "namespaced" syntax #:dumrat.bookkeeper{:ledger 2} which is equivalent to {:dumrat.bookkeeper/ledger 2}

you can disable the namespaced syntax with: (set! *print-namespace-maps* false)

Is there a more up to date version of https://cognitect.com/blog/2013/06/04/clojure-workflow-reloaded available? I've been sort of doing this with my own component system to just mess around with the system in the repl (without the reloading of various namespaces). Has anything majorly changed since this was written?

I am passing a hash-map from a one end-point to another using compojure as {:study-id 1 name "john"} but when I recieve it another end point it is converting hash-map to the string type, How can we overcome this problem?

How can I understand #' ? I saw it from https://clojure.org/guides/weird_characters#_var_quote and I known #' is var. but in realword project's code I can't understand it. like this:

(->> params
          (#'profile/create-profile conn)

(->> params
          (profile/create-profile conn)

(defn foo[x y]
  (+ x y))
(foo 1 2) =>3
(#'foo 1 2) =>3

I have a question regarding protocols and extend-protocol . Is there any reason to favour extend-protocol over modifying your code that uses defrecord? I can see that when you want to update a running Clojure instance that extend-protocol is useful. But when updating an application I would immediately favour updating the initial call to defrecord to implemented the protocol.

putting it in on defrecord is the fastest possible implementation

you are using exactly what Java leverages on the JVM to make virtual calls fast

but you could also say you have tightly coupled the type to the behavior

Can you extend protocol on things you don’t own?

yes, although there is some guidance about that

https://clojure.org/reference/protocols#_guidelines_for_extension

These make a lot of sense

See here for an example in the JS world where monkey patching led to problems (under 2.3): https://2ality.com/2022/03/naming-conflicts.html

Are there any resources or guidance about how to decide if a protocol should set :extend-via-metadata to true? Should authors default to allowing extension via metadata?

hey need some help in why compilation is throwing error CompilerException java.lang.RuntimeException: No such var: I just declared a constant name

will need a bit more information than that