Eek. I cleaned out my ~/.m2/ cache to rule out bad caching as a cause of build failure, and now I'm getting Error: Could not find or load main class clojure.main

Is there a way to restock the cache without using lein?

my project uses deps.edn

confirmed: I can go to any lein project declaring org.clojure/clojure, and run lein deps, and magically any other clj or clojure command will work

(def x 2)

(defn foo [n]
  (+ n x))

(defn bar [n]
  (+ n 2))

is foo referentially transparent?

newbie question, if i have a string “object:field=1234”, is there a way with reflection to get an object out of it?

Hi all, beginner here. In intellij cursive I ran-debug my code and exited with an error. Can I recover the REPL or do I need to restart it?

Hello! I have a list of data which I need to filter. The gotcha is that the list is ordered and the data I may be interested is often in the end of it. I read the documentation of reverse and it says it is not lazy, so I'm guessing it'll traverse all the data to reverse it. Since this given list can be very large and I want a performance gain I was hoping to traverse this list in reverse, starting from the last to first. What is an elegant way to do this without traversing the whole list (like an lazyness but from the end)? Am I worried about an tiny performance improvement (eg. reverse traverse the data but since there is no operation other than traversing it will be very quick)?

you can't do that with clojure's lists or seqs, which look like singly linked lists

but most of the ways you get a large dataset as a seq involve reading the data from some external place (a database, a file, etc) so just create the list in the reverse order from the source

but in general, if you have to do anything to a list other then operate on the head (any kind of random access, or sorting, or whatever) you might want to look at alternative datastructures

Nice, thank you

if it’s in a vector, you could loop with peek, pop.

kinda weird tho

I think I'll be changing to a vector so I can use rseq @tws

I am trying to check connection by mapping through a collection of connections and doing (query connection (str "SELECT TOP 1 1 AS access FROM" table) {:timeout 5}) but this is taking a long time. What is the better way to accomplish this?

use a connection pool library

I believe I am using a connection pool

then you shouldn't need to check connections

hmm how would I know whether I can query certain tables?

ah, I misunderstood, I thought you were checking to see if a connection is still open

are you checking to see if a table exists, or checking to see if you have permissions to access the table?

checking if I have access

most databases surface permission information as a set of tables in the database, but the way that is done is database specific

The end goal is to build a table showing what tables I have access to

I have this ugly piece of code

(into {}
      (pmap deref
            (mapv (fn [[source meta]]
                    (let [server-type (keyword (:server-type meta))
                          meta (assoc meta :source source :server-type server-type)]
                      (future (datasource-access meta)))) wb-lookups)))

But its so slow that the client times out

idk if its even slow to be honest

Ultimately it returns Connections could not be acquired from the underlying database!

because you are overwhelming your connection pool

actually the database

most databases have connection limits

But even just running one takes a good bit

so whatever database you are querying doesn't like you opening that many connections in parallel

Should I expect a single check to be quick or is it normal for it to take a while?

it is going to depend on a lot of factors, like how loaded the database is, what is in memory on the db server. I wouldn't expect that to be super slow, but I can see how it could be, and might add up reeking havoc on the db servers block cache

I would suggest looking at the documentation for your particular sql database to see how it reflects access information as tables, and query those tables instead

Got it! Ill look into just thought I was doing something wrong since it seems odd it would take that long

it takes like a minute

Hello, I'm working on a textarea component generated by reagent. This component appears after a double click and I'm struggling to understand how to put the cursor of this textarea at the end of it. Do you know how I can set the position of the cursor in this texte area please?