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

From: Sam Tobin-Hochstadt (samth at ccs.neu.edu)
Date: Fri Feb 8 11:04:30 EST 2013

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


Posted on the users mailing list.