On Thu, Jan 3, 2013 at 11:09 PM, Neil Toronto <neil.toro...@gmail.com> wrote: > (In particular, platform-independent Index and Fixnum types scare me.)
Platform-independent Fixnum is easy -- just if |x| <= 2^30, then x is a fixnum on all platforms Racket supports. [1] Index is a little trickier, since it's not documented as part of plain Racket. Typed Racket assumes that indicies are 2 bits shorter than fixnums, so `(index? n)` is true iff `(and (fixnum? n) (>= n 0) (fixnum? (* n 4)))`. Sam [1] http://docs.racket-lang.org/guide/performance.html?q=fixnum#%28tech._fixnum%29 _________________________ Racket Developers list: http://lists.racket-lang.org/dev
