[racket] Typed Racket frustration

On Sat, Jan 24, 2015 at 7:43 AM, Matthew Butterick <mb at mbtype.com> wrote:

> PS. I remain curious what one can do with an immutable `hash` function that
> takes no arguments, but perhaps it is meant to be a TR koan.

It has about the same uses as an immutable empty list. You start with
an empty table then add things to it to obtain non-empty tables.  It
is a very common occurrence in my code, and I'm sure I'm not alone in
this.