[Feature request] add an @mel attribute on object/record field to convert nullable/undefined to option

[swrup]

like @mel.return does on externals return value

[anmonteiro]

could you clarify the expected behavior of this feature request? maybe with a few code examples.

My understanding is that the reason why we don't do this for object / record fields is that they're usually inputs to a function, whereas @mel.return works on the outputs of functions.

[swrup]

I have something like this:

type config_part =
  < base_url: string Js.Nullable.t
  ; error: string Js.Nullable.t >
  Js.t

type config = config_part Js.Dict.t

external find_config : string -> config = "findConfig" [@@mel.module "my-js-lib"]

the output of my external is not a nullable itself, but an object that has nullable fields.

What I would like is to have the base_url and error fields of my object to be string option