(apply f x args)

[Orlin M Bozhinov]

Ki's implementation of apply differs from Clojure. According to ClojureDocs apply "applies fn f to the argument list formed by prepending intervening arguments to args". Only prepending. I'm interested in the second signature (apply f x args). Here is an example:

  (def pick (js require("lodash").pick))

  (defn pick1 [what key]
    (pick what key))

  (defn pickm [what keys]
    (apply pick what keys))

  (.log console (pick1 {$ "a" 1 "b" 2} "a")) // { a: 1 }
  (.log console (pickm {$ "a" 1 "b" 2 "c" 3 } [$ "a" "b"])) // {}
  (.log console (pick {$ "a" 1 "b" 2 "c" 3 } "a" "b")) // { a: 1, b: 2 }

The pick of lodash is same as underscore's and I don't think mori has an equivalent fn. If apply with three arguments worked like Clojure's apply, I believe the second console.log would have matched the third. I'm not very skilled with lispy tricks, so I wrote my own pick like so:

  (defn pick [from keys]
    (let [res {$}]
      (loop [key (.pop keys)]
        (if (js key == undefined)
          res
          (do
            (js res[key] = from[key])
            (recur (.pop keys)))))))

It would be cool if ki functions / special forms named same as Clojure / ClojureScript worked the same.

[Luca Antiga]

I agree. It turns out that mori exposes apply already, so I removed the apply implementation from ki.sjs and things works as expected now. I released 0.2.1, feel free to give it a try.

Regarding pick, I believe selectKeys does the same, check it out.

[Orlin M Bozhinov]

Thanks for apply and for pointing out selectKeys, I didn't realize it existed because it's not listed in mori's docs. It doesn't work in this case though. I believe because I'm picking / selecting from json {$} and selectKeys probably expects edn maps. So apply + underscore is a win. Btw, apply's api docs should probably be updated...

[Luca Antiga]

Updated api docs, thanks for pointing this out.