[Typing-sig] Re: Support Algebraic Data Types with @sealed

I come from the FSharp community. Thanks for considering this, ADTs are particularly missing for me in today's Python. I am used to structure all my code with them, and so is the whole community at F#. One thing I like to mention regarding the naming: @choice class I how I would define it. Not only does it say, what it does (opposite to how its implemented) it also aligns nicely with @data class @sealed doesn't say much about its usage. I am also interested about the syntax for "the next stage of the object", like in: type Shape = | Rectangle of width : float * length : float | Circle of radius : float | Prism of width : float * float * height : float How would you do that?