What's the neatest way to look for keys in a hashmap in order, running a particular function on the first one found. e.g. I've got a thing with an optional :display-name key, optional :id key and further keys. If it has a display name I want to format that, otherwise if it has an id I want to format that in a different way, otherwise ... and so on. I can use a nested if-let but it's a bit messy and condp doesn't quite work.

Plain cond should do it, no?

(defn sel [x]
  (cond 
    (:a x) (f x)
    (:b x) (g x)
    :else "nothing"))

OK, but ideally I'd want f to take an arg of whatever (:a x) is

edited 🙂

(cond
 (:a x) (f (:a x))
 (:b x) (g (:b x))
 :else "nothing")

aaah

without repeating the get

obviously that's fine but I always suspect there's a neater way in clojure.

Not sure if https://github.com/Engelberg/better-cond fits the use case

There have been discussions around better-cond some time ago, it seems a lot of Clojure shops are building some flavor of their own

This is a nice exercise for writing your own macro, I think. Mostly to expand something like

(foo x
  :a f
  :b g
  "nothing")

Now, coming up with a name for that foo is the truly hard part.

better-cond might do it, looks maybe a sledgehammer to crack a nut! I'll have a go at a macro, it's good practice anyway

Thanks orestis

Yeah I get it — but sometimes adding a library like that to your dependencies early on saves you for having to judge cost/benefit for every little bit tiny use case.

If you have it, might as well use it in many places, I mean.

hey, looking to make friends. dont have any

Hey, does anyone have any other video/blogs that talk about Clojure at scale? like this https://www.youtube.com/watch?v=av9Xi6CNqq4 or Rich Hickey's Language of the System.

what am i missing here?

(match '("M" "125.4,69.7" "rest1" "rest2") 
       [(["M" x & rest] :seq)] x
       :else :no-match)
=> :no-match

Hi , my compjoure route is (GET "/foo/:a/:b/:c" [a b c] (some-controller/controller-function a b c)) it is not working when my url is like localhost:8080/foo/1-2-3.html#/foo/bar

I'm struggling to get spec/fdef to fire anything useful.

(require '[clojure.spec.alpha :as s])
(s/def ::name string?)
(s/def ::score int?)
(defn generate-new-player
  [name]
  {::name name
   ::score 0})

(s/fdef generate-new-player
        :args (s/cat :name ::name))

(s/explain ::name 42)
; => 42 - failed: string? spec: :user/name
(generate-new-player 42)
; => {:name 42, :score 0}

Hi there, dear Clojurians: Can you tell me how is next different than rest?

Style question. When destructuring complex data structures, my linter (`joker`) gives a warning for unused binding when I use the :as <complex data structure>, but to me (and examples I've seen) it seems good practice to include that to let folks know what data structure the function is looking for.

Is passing function calls as arguments bad practice?

can you put an example?

(fn1 some-arg (fn2 args)) where fn2 returns some data

if you were to let bind all of those it would get ugly. this is a "salt to taste" situation.

sometimes makes sense sometimes not

an easy example to see is in arithmetic. (+ (+ 2 3) (* 3 4) (/ 9 3)) would look silly if each of the intermediate steps was in a let binding

good example, yeah I'll put more common sense to it 😉

its a good question. but the answer is to just make it legible

Would be a problem to create tests outside the test/ folder in a lein project? I guess is not a problem in clojurescript as I define what's the entry point and there's the closure compiler for not used functions, but I don't know if similar things happen in the JVM.

the test/ folder is just a classpath entry that is automatically used by leiningen (and other tools) when you ask it to run tests, any other directory can be used if you properly make your tool use it when running tests

there's a leiningen config for folders to include when running tests

;;; Filesystem Paths
  ;; If you'd rather use a different directory structure, you can set these.
  ;; Paths that contain "inputs" are string vectors, "outputs" are strings.
  :source-paths ["src" "src/main/clojure"]
  :java-source-paths ["src/main/java"]  ; Java source is stored separately.
  :test-paths ["test" "src/test/clojure"]
  :resource-paths ["src/main/resource"] ; Non-code files included in classpath/jar.

(from lein help sample)

Any number to currency formatters out there for clojure?

:tests-paths seems to work

I'm having trouble getting connected to ms sql server:

Caused by: java.lang.Exception: Unsupported URI:  please, submit an issue request and we'll try to add it. Pull requests also welcome

the docs here: https://en.wikibooks.org/wiki/Clojure_Programming/Examples/JDBC_Examples#Microsoft_SQL_Server make it look correct. i'm just wondering if this URI really isn't supported.

@bill.h.tucker I suspect that wikibooks page is horribly out of date...

Oh gosh, yes, it's completely different to how you use that library these days 😞

What version of clojure.java.jdbc are you trying to use?

More up to date documentation is here http://clojure-doc.org/articles/ecosystem/java_jdbc/home.html (and that is linked to from the GitHub repo for the project https://github.com/clojure/java.jdbc/ )

You're better off using the :dbtype hash map form of db-spec -- it's the preferred way and it's much better supported that raw URI strings.

for your case it would be

{:dbtype "sqlserver" :dbname "DDDDD" :host "HOSTNAME" :user "UUUU" :password "XXXXX"}

Assuming you have a modern version of clojure.java.jdbc (0.7.9 is current) and you also have the Microsoft SQL Server JDBC driver in your dependencies.

Example (for deps.edn): https://github.com/clojure/java.jdbc/blob/master/deps.edn#L18-L19

In project.clj, that would be [com.microsoft.sqlserver/mssql-jdbc "6.2.2.jre8"]

Also, feel free to ask any detailed questions about clojure.java.jdbc or database stuff in #sql (it's lower traffic and I'm more likely to see it there) @bill.h.tucker

Ah, at least it looks like someone updated that wikibooks page to warn people the docs are out of date For the latest, most up-to-date community-managed documentation for the clojure.java.jdbc library, consult Using java.jdbc on Clojure Documentation. This WikiBooks page is written around a very old version of the library and most of the examples here will not work with newer versions. 🙂

thanks for your help. I've been struggling with this for weeks.

..off and on.

Sorry to hear you've been struggling, especially for weeks 😞

If it's not obvious, I'm the maintainer of clojure.java.jdbc (and the upcoming alternative for it, next.jdbc), and I test it against ten databases, including MS SQL Server although my heaviest use of it is for MySQL (Percona 5.7) at work.

thanks for your help.