WIP: with- keyword support for anonymous records

[vzarytovskii]

This is pretty much a WIP or an experiment of adding a without (or with-) keyword support for anonymous records.

Note: things may change (e.g. keyword itself (as many people don't like with-), implementation details, language switch, etc).

RFC: https://github.com/fsharp/fslang-design/blob/main/RFCs/FS-1072-without-anonymous-records.md

Discussion: fsharp/fslang-design#616

Things to be done:

• Lexer/parser with- support for anonymous records expression.
• Actual logic to remove fields when creating new AnonRecd.
• Tests

[nojaf]

Could we have the range of the with- keyword in the tree as well?
This would be useful for Fantomas if the code has a comment after the with- for example.

type A = { X: int; Y: int }
let a = { X = 1; Y = 2 }
let b = {| a with- // foo 
                                  Y |}

[Happypig375]

This would be quite a use case for #6941

[Happypig375]

I would expect a with- to always remove the field. When the fields already present are controlled elsewhere, I would want this to be a guarantee.

[Happypig375]

The flow of fields should allow an empty state where more fields can be added later.

[KevinRansom]

Closing, two years without attention, please reopen if you want to work on completiong this.

Thanks

Kevin

[vzarytovskii]

Gonna close it for now, needs more thinking in regards of spread operator