On Thu, May 31, 2012 at 12:21 PM, Neil Toronto <[email protected]> wrote: > On 05/31/2012 09:50 AM, Sam Tobin-Hochstadt wrote: >> >> On Thu, May 31, 2012 at 11:42 AM, Neil Toronto<[email protected]> >> wrote: >>> >>> Currently, the floating-point bitmap type is defined so that its size >>> fields >>> are Integer, and a guard assures that they're really Nonnegative-Fixnum: >>> >>> (struct: flomap ([values : FlVector] >>> [components : Integer] >>> [width : Integer] >>> [height : Integer]) >>> #:transparent >>> #:guard >>> (λ (vs c w h name) >>> (with-asserts ([c nonnegative-fixnum?] >>> [w nonnegative-fixnum?] >>> [h nonnegative-fixnum?]) >>> [...] ; elided length check on vs >>> (values vs c w h)))) >>> >>> >>> What I'd *really* like, though, is to have the fields be >>> Nonnegative-Fixnum >>> in the first place, and simply have a more permissive constructor. Is >>> there >>> a way to do that? As it is, `flomap-components' always returns an >>> Integer, >>> but no flomap instance can actually have an integer-valued `components' >>> field. >> >> >> Could you just structure the program this way? >> >> (struct: flomap ([values : FlVector] >> [components : Nonnegative-Fixnum] >> [width : Integer] >> [height : Integer]) >> #:transparent) >> >> (: make-flomap : FlVector Integer Integer Integer -> flomap) >> (define (make-flomap v c w h) >> (with-asserts ... (flomap v c w h))) > > > I could, but `make-flomap' is already defined and used extensively (it's an > analogue of make-flvector).
You should be able to fix this with a `rename-out', presumably. > Also, not using the structure name to create > instances from their field values now makes me feel dirty. :D I'm not sure I can help with that. ;) -- sam th [email protected] ____________________ Racket Users list: http://lists.racket-lang.org/users
