[racket] specifying types for fields in non-polymorphic structures

But then the posn constructor doesn’t enforce that it’s arguments have to be Reals, and the posn? predicate doesn’t check it, and the accessors don’t say that they always produce Reals.  

On Apr 25, 2014, at 9:49 PM, David Van Horn <dvanhorn at cs.umd.edu> wrote:

> How about this?
> 
> (struct: (x y) posn ([x : x] [y : y]))
> (define-type Posn (posn Real Real))
> (define-type Origin (posn Zero Zero))
> 
>