(defn foo []
  (s/def ::baz string?))
(foo)
(s/valid? ::baz "baz")

(defn fii [k]
  (s/def k string?))
(fii ::faa)
(s/valid? ::faa "buzz")

Hi everyone! Very new to clojure and im am trying to figure out how I can implement a java interface and some new additional fields to the class. For example - https://kafka.apache.org/0110/documentation/streams/developer-guide#streams_processor_process How would i declare kvStore so its accessible on this.

(reify Processor
           (init [this ctx]
             ((fn [ctx]
                (println "Processor Initialized: " ctx)
                (set! (.kvStore this) (.getStateStore ctx "user-store") ))
              ctx))

           (process [this k v]
             ((fn [key value]
                (println "Processing Message: " key value)
                (println "The Store: " (.kvStore this))
                (KeyValue. key value))
              k v))

           (close [_]
             ((fn []
                (println "Closing"))
              )))

I basically need to add a new instance field member to the class.. not sure how to do this.

I think i found a hint that exposes it as an atom..

Does anyone have any experience plugging a database pooling library like Hikari into hugsql? I'm calling my hugsql fucntion like so

(db/insert-account db/datasource {:password "password" :email ""})

Can someone help me build a project with lein? I have a new project made with

lein new app test-foo

cd test-foo
lein uberjar
Compiling test-foo.core
Created /home/stuart/Source/clojure/test-foo/target/uberjar/test-foo-0.1.0-SNAPSHOT.jar
Created /home/stuart/Source/clojure/test-foo/target/uberjar/test-foo-0.1.0-SNAPSHOT-standalone.jar

(base) stuart@stuart-Z87M-D3H:~/Source/clojure/test-foo$ java target.uberjar.test-foo-0.1.0-SNAPSHOT.jar
Error: Could not find or load main class target.uberjar.test-foo-0.1.0-SNAPSHOT.jar

(ns test-foo.core
   (:gen-class))
(defn -main
    "I don't do a whole lot ... yet."
    [& args]
    (println "Hello, World!"))

(defproject test-foo "0.1.0-SNAPSHOT"
  :description "FIXME: write description"
  :url ""
  :license {:name "EPL-2.0 OR GPL-2.0-or-later WITH Classpath-exception-2.0"
           :url ""}
  :dependencies [[org.clojure/clojure "1.10.1"]]
  :main ^:skip-aot test-foo.core
  :target-path "target/%s"
  :profiles {:uberjar {:aot :all}})

OK, I realise my mistake, I need to do

java -jar target/uberjar/test-foo-0.1.0-SNAPSHOT.standalone.jar

this is an extremely common mistake, making me think the app behavior is broken

i need to learn how java actually works 😄

it makes sense to create the jar as a subtask of making the uberjar, but leaving it there to be used instead of the uberjar is a design flaw

do you know any good tutorials for using graalvm to make a native binary from my uberjar? So i get a quicker start up time?

I don't recommend this as a beginner task

there are a lot of things within clojure you can't use, or have to use differently, in order to make that work

if you want an easy way to have graalvm and fast startup from the beginning, you could use babashka though

https://github.com/borkdude/babashka

it doesn't support all of clojure, but neither does graalvm, and it did a bunch of the hard stuff for you

Thanks, I'll take a look

Hey team, I'd love to turn this -> into a lazy sequence

(defn get-all-users []
  (loop [ret []
         page (-> (FirebaseAuth/getInstance)
                  (.listUsers nil))]
    (if page
      (recur (concat
               ret
               (map user-record->map (.getValues page)))
             (.getNextPage page))
      ret)))

(->> (get-all-users)
        (pmap do-some-work))

using lazy-seqs with side effects / external resources is messy

that said, the get-all-users could turn into something like (mapcat :values (iterate (fn [{:keys [page]} (let [nxt (.getNextPage page)] {:page nxt :values (.getValues nxt)}) ...)

There's a new function under consideration for Clojure 1.11 which makes it easier to iterate over side-effecting things that produce data in pages -- you could use the code from the Jira issue until that lands.

the big problem with the code you have now is a stack of concats that could blow up

concat and imperative looping don't mix nicely

oo (mapcat :values (iterate (fn [{:keys [page]} (let [nxt (.getNextPage page)] {:page nxt :values (.getValues nxt)}) ...) looks great! Thanks team. Noob q: mind expounding on stack of concats that could blow up ? What do you mean? (if blow up stack frame, i thought loop avoided that)

https://stuartsierra.com/2015/04/26/clojure-donts-concat

(I think that blog post covers it)

Yup, it even gives the loop/`concat` example to show the problem...

@stopachka I recommend the blog post but the tl;dr version is that a lazy-seq (the thing you are trying to understand here), works by turning "next" into a thunk (cached function of zero arguments)

calling concat on concat without yet forching the result, leads to a massive call stack before any work happens

https://clojure.atlassian.net/browse/CLJ-2555

this is great. thanks team!

(Stuart's whole Do's/Don't series is good reading, BTW @stopachka)

> So we have a stack overflow. But why? We used recur. Our code has no stack-consuming recursion. Or does it? (cue ominous music) xD love the writing. Will look deeper