At Wed, 13 Jul 2011 12:25:42 -0400, Sam Tobin-Hochstadt wrote: > > On Wed, Jul 13, 2011 at 12:08 PM, <[email protected]> wrote: > > > > ;; we assume indexes are 2 bits shorter than fixnums > > ;; We're generating a reference to fixnum? rather than calling it, so > > ;; we're safe from fixnum size issues on different platforms. > > -(define (index? x) (and (fixnum? x) (>= x 0) (fixnum? (* x 4)))) > > +(define (index? x) > > + (and (fixnum? x) (unsafe-fx>= x 0) (fixnum? (unsafe-fx* x 4)))) > > How is this possibly ok? If `x' is (/ MAX_FIXNUM 2), then this code > has no semantics.
Good point, the multiplication is unsafe. I'll fix that. Vincent _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev
