Add `dict.change`? about stdlib HOT 8 CLOSED

Let's use the name "update" after this has been actioned: #570

from stdlib.

OCaml's stdlib calls this update
OCaml's Base (stdlib replacement) calls this change
Haskell's containers calls this alter
Elixir's Map has get_and_update

OT: Reminds me of gleam-lang/gleam#1645
Maybe that idea could include an optional explanation why that alias exists, e.g. "similar to elixir get_and_update" or "reimplements ocaml update"

from stdlib.

#570 has the update function becoming something like this:

dict.update return Result and Error if no key found

Which does make sense if the current update is renamed to upsert imo, given the sql naming of update/upsert. Whereas this function would need some other name.

from stdlib.

I have re-read your proposal and AFAIU it now, change works on dicts with keys that can exist or not exist and depending if they exist or do not exist they can handle those cases by injecting values or even removing values if a key existed all depending on the apply function of the change call? I hope I got it.

I think update does not communicate that, update does not communicate that something is removed. alter or change communicate that something could be removed. Now that we have upsert I am in favour of alter over change but that's just me.

from stdlib.

Closing this to track in the other issue. Thanks folks!

from stdlib.

@mooreryan is this the impl you meant? #659

from stdlib.

@mooreryan is this the impl you meant? #659

Looks like it, though I don't think that the function in that pull request should be called update. The callback in that PR is also returning a Result--that would not be my preference, however, I don't have a strong opinion about that aspect.

from stdlib.

I think the general policy is that we do not return Option.
I agree that it should be called change.

from stdlib.