Hi #beginners.

I been diving in hard over the last week or so but when I felt ready to port a neglected but in-production django app, I started getting disoriented

Is anyone present who cares to discuss porting a Django app?

If I use something like reaver which is a thin wrapper for Jsoup, when I add org.jsoup/jsoup in my deps.edn, does that override the version used by reaver?

I believe so, an explicit version in your deps will override any transitive dependency. You can always check by doing clj -Stree and examining the output.

Is there any doc which gives more info while debugging a macro? or which library can be used to debug macro efficiently?

Have a problem that i currently cannot see any way to solve. I have a vector [:header] and another vector

[[[:A]
  [:B]]
 [[:C]
  [:D]]]

[:header 
  [:A]
  [:B]
  [:C]
  [:D]]

Hi, should I use func! if it changes agents/atoms/etc as a side-effect or it’s fine just func? what’s your preference? thanks

Hi, clj question. I’m trying to mess around with buddy in the repl. { :deps {buddy/buddy-core {:mvn/version "1.10.1"} buddy/buddy-hashers {:mvn/version "1.8.1"} buddy/buddy-auth {:mvn/version "3.0.1"}} } That’s my deps.edn (the only file in the working directory). I run clj, the libs download, but then I (require '[buddy/buddy-hashers]) and it fails with Could not locate buddy_auth__init.class I sense I’m missing something basic here.

@james.amberger should that be (require '[buddy.buddy-hashers]) , actully it seems it should be (require '[buddy.hashers]) , so ideally I would use an alias, so really it would be (require '[buddy.hashers :as hashers])

Examples are in the user guide https://funcool.github.io/buddy-hashers/latest/user-guide.html

Thanks john; (require '[buddy.hashers]) did the trick

How to get syntax highlighting and tab completion in my repl?

For syntax highlighing and tab completion • in a terminal repl, use rebel readline • For emacs use Cider and/or Clojure LSP • For VS Code, use Calva (which uses Clojure LSP) • For intellij, use Cursive • For NeoVim, use Conjure, CoC and Clojure LSP

I had rebel readline in my deps.edn before but I did not hvae colors/completion. I tried to look around for necessary additional steps

This is how I use rebel readline https://practical.li/clojure/clojure-cli/repl/

I don't focus my comforts on the REPL as much as an editor-connected REPL

I almost never type into my REPL directly

Yeah I have vim-fireplace working

It’s very cool

ahh, much better. Thanks John

When using Neovim, I use the following configuration https://github.com/rafaeldelboni/nvim-fennel-lsp-conjure-as-clojure-ide There may be some ideas you could borrow from it also.

Rebel Readline is a very effective terminal UI to the REPL process and very handy when you dont have an editor connected to the REPL. Obviously it wont have all the syntax highlighting and completion available from a complete Clojure IDE or if using Clojure LSP, but they do require a little more investment to setup.

online help with rebel readline ?

rebel readline has eldoc, so should function arguments as you type. There is also a key binding to show docs - type :repl/key-bindings to see the current key bindings

https://github.com/bhauman/rebel-readline#key-bindings

If more than that is needed, then either use a web browser or move to an editor / ide connected REPL setup

I used com.github.seancorfield/next.jdbc   {:mvn/version "1.2.761"} in deps. call create table sql show error: ; Execution error (ClassCastException) at next.jdbc.prepare/create (prepare.clj:94). ; java.lang.Character cannot be cast to java.lang.String

(def mysql-db {
                 :dbtype "mysql"
                 :dbname "bzst_db"
                 :user "root"
                 :password "root"
                 :jdbcUrl "jdbc:"
                 }    )
  
  (def schema-account-holders-table
    ["CREATE TABLE account_holders (id VARCHAR(32) NOT NULL"])
  
  (create-tables! schema-account-holders-table mysql-db)

Umm…so I’m looking around for a clojure way of performing some maths with numbers where numbers could be doubles, ints, rationals, big decimals. Specifically I was hoping for a sqrt (among others) function which would work with big decimals but would not break if called with some other type. Something like:

(with-precision 10
  (.sqrt 3M *math-context*))

preferably there should be some attempt at retaining types, i.e. if I use doubles it should produce doubles, if I use BigDecimal it should procuce BigDecimal etc

this seems kind of basic but I came up empty after some attempt at googling

I guess I can implement this myself via a defmulti and delegation to the java methods

just figured there would be something out there

I think there is kind of no man's land between enterprise kind of systems where math isn't a huge priority, and machine learning systems where math is a huge priority

like the one is likely to just "solve" this kind of issue by just using bigdecimals, the other is all matrices, possibly off heap, where you want to avoid bigdecimal

where there is a significant interest in math, it seems to fall more on symbolic manipulation of equations

https://github.com/sicmutils/sicmutils kind of thing

@hiredman thanks for that…a lot of good stuff in sicmutils…will need to stare at that code for a while to see if it covers my needs but definitely looks promising

Trying to decode base64

This is proving difficult. I have imported Base64$Decoder

but I can’t seem to call getDecoder no matter what I do

In clj or cljs?

clj

(made me look though!)

Ok, the easiest way to decode Base 64 is to use the static method: Base64/decodeBase64

(.decode (java.util.Base64/getDecoder) b) will work, but you'll want to annotate the type of that param.

hmm

ok, looks like I didn’t actually call getDecoder

Yeah, that kind of bug is particularly difficult to spot.

how can I call Base64/decodeBase64?

I don't know where that method exists.

That’s a static method on the class.

Are you referring to org.apache.commons.codec.binary.Base64?

java.util.Base64/decodeBase64 gets me Unable to find static field

Ah, wait, I’m referring to an old project, and it’s pulling in org.apache.commons.codec.binary.Base64, yeah

ah ok

but also

Sorry about that, I forgot I’d pulled that in.

Try the one I posted above. It should work for you.

isn’t this kind of static this, return a ‘Decoder’ that stuff the very sort of thing we hope to avoid by using clojure?

https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/Base64.Decoder.html is the java docs for the decoder; and you get it from https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/Base64.html

It is, and you could find or write your own wrapper function for it. That's what I use. But interop is interop.

so I would have to make a simple function out of it myself, not hard but

yeah

gotcha

dev=> (let [decoder (java.util.Base64/getDecoder)]
 #_=>   (seq (.decode decoder "1234")))
(-41 109 -8)

Clojure is hosted within a platform, and aims to reuse / leverage all the existing correct code

pro tip: always paste what you tried

k thanks, I will

(The Java Base64 methods are getting SIMD acceleration soon)

(reuse/leverage >>> uncomfortable interop)

@ghadi can you rephrase that?

which piece?

last, what’s SIMD acceleration, and what’s that >>> relation mean

SIMD acceleration is a way to improve performance of algorithms like base64: do things a block at a time, rather than byte at a time >>> meaning just "way better than"

thanks

@james.amberger FWIW, I used to be a big fan of wrapper libraries when I first got started with Clojure years ago but I've come around to preferring direct interop these days -- unless you are writing .cljc code and need portability between Clojure and ClojureScript.

yeah, I have seeen ‘cljc’ a couple of times now. What is it?

some kind of precomiled

classes?

.cljs is ClojureScript, .clj is Clojure, .cljc is accepted by both Clojure and ClojureScript

ah

ok

So you can have conditional (read-time) code in .cljc files to allow you to share logic between frontend and backend.

that’s appealing

read-time = compile time for cljs?

It's more and more possible these days to write portable code -- see https://github.com/seancorfield/honeysql/blob/develop/src/honey/sql.cljc which only has four conditionals in it (see https://github.com/seancorfield/honeysql/blob/develop/src/honey/sql.cljc#L172 for example).

Read-time means read-time. Parsing. Pre-compilation.

very cool

yeah the more I look at this the more it seems that where in Python or TS I would have been reaching for a library, in Clojure I’m supposed to just do it

clojure.core is very powerful, and the whole of the Java standard library is also right there "just below the surface". A lot of batteries included.