Clojurians Log v2

ah it's because of first and rest of the form

(some-> maybe-fn (apply []))??

sure, there's ways to work around it

I feel like it wouldn't have occurred to me that (some-> maybe-fn ()) would work ... but now you mention it, it's interesting that it doesn't 😉

Yeah I ended up with when-let

some-> is so close to optional chaining like foo?.bar?.baz?.()

I wonder if it’s possible to change the implementation to allow:

(some-> foo (.-bar) (.baz))

doesn't that already work?

for all but the last part to make baz?.() work

yes it does:

cljs.user=> (some-> #js {:bar #js {:baz (fn [] (prn :dude))}}  (.-bar) (.baz))
dude: 

oh the last part ok

yeah then -> needs to change

which I'm all for

but it's probably not going to happen

here’s a safe-> macro that works: https://gist.github.com/shaunlebron/0950a2a2e65beec6c121dff3de6309f1

Something else that comes to mind is that dissoc is the inverse of assoc. But that only holds true for maps and sets. I don't think all cases of assoc followed by dissoc on a vector brings you back to the original vector value.

I think this is what was tripping me up

because it cannot not have the key. notice assoc on vectors fails outside of the length of it.

settings=> (assoc [] 0 :hi)
[:hi]
settings=> (assoc [] 4 :hi)
Execution error (IndexOutOfBoundsException) at metabase.analytics.settings/eval294488 (REPL:20).
null
settings=> (assoc [] 1 :hi)
Execution error (IndexOutOfBoundsException) at metabase.analytics.settings/eval294490 (REPL:21).
null

settings=> (assoc [:not-empty] 1 :hi)
[:not-empty :hi]

but you cannot have a vector [:first :second <literally no value here> :fourth] . There’s no way for a sequential structure to not have a third item

Couldn't it have natural number keys to dissoc? I'm not sure I follow

if you removed the first item from this vector, what would you expect the resulting structure to be? [0 1 2] ?

I would expect (dissoc [0 1 2] 1) to return [0 2]

wouldn’t that still have an item at index 1 though?

You're saying because of the underlying data structure?

> clojure.core/dissoc > ([map] [map key] [map key & ks]) > dissoc[iate]. Returns a new map of the same (hashed/sorted) type, > that does not contain a mapping for key(s). the docstring says won’t have that key any longer. but your return value does have a value

settings=> (get [0 2] 1)
2

how can you remove the key 1 , or the notion of “the second item” in a vector ?

oh I see what you're saying 🤦🏻‍♀️

yeah. it’s possible it could “pop” off the end but it doesn’t do that. the same way you can assoc a new element at the end, or replace in the “interior” of the vector