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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