OCaml like variance annotations (+'a and -'a)
There is a new community-driven user voice site for managing suggestions specifically related to the F# language design. https://fslang.uservoice.com/forums/245727-general
Please move this item there and link back to this entry, as the Visual Studio User Voice site is best used for suggestions related to the Visual F# Tools (rather than the language itself).
Don Syme, for the Visual F# Tools team