hi there! I am not sure that this is a right place for asking that. But, I’ve started to learn clojure a week ago and want to ask you guys to review my PR. Nothing complicated there. I’d like to hear any issues with style or more elegant ways to do something. Will appreciate your help. https://github.com/finomayato/ad-astra/pull/1

Is there a way to pass a function to another function (or macro) that contains a macro? Maybe my specific example will make this more clear. I’m trying to make this work: (.... foo [f] (meta #'f)) but i’m a bit rusty on macros and i’m having trouble understanding my options.

(defmacro foo [f] `(meta (var ~f)))

I’m guessing because the meta macro happens at compile time i can’t do this

Sorry, got it right now... slack markdown problems.

This works! Thanks. Huh, i must not understand something about how macros work.

I guess you can also write it as

(defmacro foo [f] `(meta #'~f))

Well, if you macroexpand it you can see it turns into what you want. But is there some aspect that is not clear?

1) right so defmacro stops evaluation of the passed arg 2) ` means dont eval anything inside this until returned 3) ~ means execpt eval this? argh. i need to re-read how everything works it seems

(By the way, foo can't be written as a function; if so f would be a function object, associated with 0, 1 or many vars, and you can't find out inside the function)

Yes, I have read Colin Jones's book once a year at least for the past several years.

kk. I have all the books, so i’ll just refresh my memory.

@drewverlee The syntax quote stuff prevents the need for writing harsh stuff like

(defmacro foo [f] (list 'meta (list 'var f)))

Perhaps understanding of syntax quote also involves realizing that it works outside of macros. Hrm.

As in

(let [x [1 2 3]] `[:a :b ~@x :c])

Or, perhaps the simplest:

`x

@mathpunk the ring wrap-params middleware will put the request body into a key on the request - but even without that you can find the body in that request map. Recall that the req is a hash map, you can look at what's stored under the keys, and you can make middleware that puts things under new keys.

I’m doing this inside some cljs code:

(set! (-> @chart .-data .-datasets (aget 0) .-data) (clj->js (reverse temps)))

(oset! @chart "!data.!datasets.!0.!data" (clj->js (reverse temps))

@duminda one option is to use some-> which short circuits if any value is nil

or do you want to create index 0 in .-datasets if it isn't there?

@noisesmith: yes I want to add element if it’s not already there.

(.. (OctetSequenceKey$Builder. k)
         (keyID kid)
         (algorithm (or alg alg-a128kw))
         (keyUse (KeyUse/ENCRYPTION))
         (build)
         (toSecretKey "AES")))

@sb .. is the interop equivalent of ->: (.. o foo bar) expands to (. (. o foo) bar)

@sundarj thanks, in this case “similar”!

How to correctly distinguish prod and dev environment when running web application via uberjar? I am using Environ for setting the dev and prod property and I have a profiles like this (no vars are being set)

:profiles {:uberjar {:aot :all}
                  :env (:prod "true}
             :test {:dependencies [[midje "1.9.0-alpha5"]]
                    :plugins [[lein-midje "3.2.1"]]}
             :dev {:env {:dev "true"}}}}

@drewverlee Macros are certainly a slippery concept. I have to remind myself over and over: Macros run as the code is being compiled. When you pass an argument to a macro the macro sees the argument more or less as you wrote it in the source (that's all it has at compile time). The macro takes its arguments and does its thing and returns the code that should be compiled. The syntax quoting thing ` is a separate feature, but one that is really handy for writing macros. Syntax quoting is a lot like HTML templating in a we application.

@noisesmith @lee.justin.m @joelsanchez thanks for the resonating yesterday, and also the practical tips!

can't say it was very encouraging though 😉

@joelsanchez thanks for pointing at data-specs!

oh no embarrassing...I think I found my mistake

so the print shows up when reentering the map from another page but it is not updating

I thought I'd just start examining what req looked like as I learned how compojure works, but I'm stumped

Hello. I'm a Clojure newbie and was wondering if anyone here has used both Clojure and Common Lisp extensively?

depends on your definition of "extensively" in my case (years of clojure at work, vs. I made a few toy things to learn common lisp) - but if you have specific questions there's likely someone who can answer

I did learn common lisp (and scheme) before clojure though