[racket] TR: Making recursive types as subtypes of non-recursive types

On 02/22/2012 05:35 PM, Sam Tobin-Hochstadt wrote:
> You're very close -- you just need to give inference a little more
> help.  This definition works:
>
> (: card* (All (a) ((Set* a) ->  Hereditary-Set)))
> (define (card* A)
>    ((inst card (U a (Set* a))) A))

Ah, excellent. Thanks!

> My brain was injured thinking about those types, though. :)

I'll take that as a compliment. :D

Neil ⊥