[racket] (Math) Computing the mean is slow in Typed Racket

On Fri, Feb 8, 2013 at 11:00 AM, Neil Toronto <neil.toronto at gmail.com> wrote:
>
> Another option is to do something with Typed Racket to get rid of this type
> error, which makes the cast necessary:
>
>   Type Checker: Expected (Listof Real), but got
>   (U (Listof Real) (Pairof Any (Listof Any)))
>
> I don't know why it does this, but there might be a good reason. Vincent?

The behavior of `list?` is not right -- something needs to be changed
so that it doesn't cause the type system to forget what it previously
knew.

Sam