Hadrian Tang

The concrete reason why this syntax doesn't compile: ```fs open System.Runtime.CompilerServices module Accessors = [] extern byref resizeArray) ``` is because of ``` error FS0010: Unexpected type application in extern...

These two compile differently. One is C#-interoperable and can only extend methods, while the other is F#-specific and can extend anything about the type.

You do know that the F# compiler generates an opaque resource blob that is not visible in decompilation, right?

Please don't make `mod` a normal identifier. [RFC FS-1114](https://github.com/fsharp/fslang-design/blob/main/FSharp-6.0/FS-1114-ml-compat-revisions.md) explicitly omitted `mod` because of the future possibility of - https://github.com/fsharp/fslang-suggestions/issues/1065