Visible type application for `thruIn`?

[ntwilson]

This stems from this discussion on Discourse.

Right now it is impossible to call fetch with a still-unknown record for the options, even if you copy all the constraints straight from fetch. E.g., this will not compile:

fetch2 
  :: forall input output thruIn thruOut headers
  . Union input thruIn (HighlevelRequestOptions headers String) 
  => Union output thruOut UnsafeRequestOptions 
  => ToCoreRequestOptions input output 
  => String 
  -> { | input } 
  -> Aff Response
fetch2 = fetch

The trouble is that the compiler can't solve for thruIn used by fetch, because the thruIn of fetch2 isn't known to be the same type as thruIn for fetch. When this library gets updated to purescript 0.15.10, would you consider making thruIn a target of a visible type application so that this would compile?

fetch2 
  :: forall input output thruIn thruOut headers
  . Union input thruIn (HighlevelRequestOptions headers String) 
  => Union output thruOut UnsafeRequestOptions 
  => ToCoreRequestOptions input output 
  => String 
  -> { | input } 
  -> Aff Response
fetch2 = fetch @thruIn

My understanding is that the visible type application is optional, so if you're applying fetch to a real concrete record, you can leave the type application off, and the usage would be unchanged to what it is now.

[sigma-andex]

I don't see any problems with adding this. However I'm thinking if we can maybe get better than this? It is ok like it is now if you use fetch directly, but I also noticed that it gets unwieldy if you want to create a function that sets certain parameters.

[ntwilson]

Thanks! Is there any way I can help? I don't know of a good approach myself to be able to set certain parameters without either using some kind of library for handling optional fields like convertable-options or untagged-union, or else just having a concrete record with a default value defined that you can do an update on. Do you have any ideas how you would want to handle it?

[pete-murphy]

There was another possible use case for fetch with VTA here: https://github.com/purescript/registry-dev/pull/657#discussion_r1304950084

[sigma-andex]

@pete-murphy thx, just saw it. created #10 , this should fix this, right? @ntwilson @pete-murphy

[sigma-andex]

Sorry for the delay, haven't been doing much Purescript lately. I have drafted a new release v3.0.0. Not sure what is needed nowadays to publish a new release to the registry given that this requires v0.15.10 @thomashoneyman

[pete-murphy]

Seems like this has been closed by #10 right?