Vincent got TR to 'split' complex numbers, if that's what you mean by 'wide enough' arguments, and he did so w/o changing R. So perhaps there is a way to get the computation on floats and the tag for their meaning.
On Aug 18, 2012, at 4:13 PM, Robby Findler wrote: > One could, concievably, still do that without boxing/unblocking by passing > "wide enough" arguments. And it does seem like TR could help with that, but > IIUC the untyped portion of the compiler needs significant work to support > that before TR's knowledge of the program would help (But doing a better job > with structs is, iiuc, a long standing "something could be much better here" > type of thing.) > > On Saturday, August 18, 2012, Matthias Felleisen wrote: > > But don't you need the 'tag' from the struct to distinguish .4 in p from .4 > in 1-p? They may be the same number but they denote distinct ideas. -- > Matthias > ' > > > On Aug 18, 2012, at 2:40 PM, Neil Toronto wrote: > > > Is TR's optimizer eventually going to unbox structs in the same way it > > unboxes rectangular flonums? > > > > I have a design choice right now: how to represent probabilities. Floats > > are good because of their speed, but because of floating-point limitations, > > *four different representations* are typically used. (For the curious: p, > > 1-p, log(p), and log(1-p).) I'd like to make functions that accept any one > > of these representations, denoted by this type: > > > > (define-type Probability > > (U probability 1-probability log-probability log-1-probability)) > > > > The types are simply struct types that tag Float. > > > > Of course, manually boxing flonums ruins any chance of the compiler > > emitting code that keeps the flonums unboxed. If TR's optimizer unboxed > > structs, though, everything could be speedy. > > > > FWIW, by "eventually," I mean "within the next n years", where "n" is a > > smallish number. > > > > Neil ⊥ > > _________________________ > > Racket Developers list: > > http://lists.racket-lang.org/dev >
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