At Sat, 18 Feb 2012 21:47:52 -0600, Robby Findler wrote: > On Sat, Feb 18, 2012 at 9:39 PM, SF <sf.ro...@gmail.com> wrote: > > On Sat, Feb 18, 2012 at 9:18 PM, Robby Findler wrote: > >> I'm not sure of the precise answer, but I don't think that all floats > >> (even the integers) have a corresponding fixnum. > > > > My C brain wonders why I can't just cast it to get the lower bits, I > > don't care about overflow. > > I'm not sure if this will fit in with how Typed Racket works, but I > guess you could write an ffi-based function that actually fiddles with > the low-level representation to just get at the bits you want. > > But, actually, I think that maybe that won't work because Racket's > floats are usually boxed, unless the compiler can "see" everywhere > they go and can manage to pass around unboxed versions (something that > TR facilitates, I believe). So, if you were to pass them off to an > unknown (from the compiler & TR's perspective) function, then they'd > fall back to boxing and you'd lose all the efficiency gains. > > I guess there would have to be some new primitive added to make this work. > > Of course, I could be missing out on one of the existing prims. Maybe > one of the TR/runtime system experts'll fill us in.
`fl->fx' does what he wants, but only if the input float actually represents an integer. Vincent ____________________ Racket Users list: http://lists.racket-lang.org/users
