[racket-dev] What are single flonums good for?

At Sun, 16 Sep 2012 17:10:01 -0500,
Matthias Felleisen wrote:
> Suppose we had started Racket long ago and maintained it until
> now. Then we'd be looking at 8bit, 16, 32, and 64 precision. In some N
> years from now, we may need 128. (Actually there were machines in the
> past that did, but never mind.)
> 
> Could we separate precision and type into separate dimensions so that
> we could state types like this:
> 
>   ∀ p : precision. FP[p] -> FP[p] 
> 
> where we see FP as a type constructor that consumes a precision value
> to generate the right kind of type. This might be a dependent type but
> it could be a useful one. Of course, it isn't really a parametric form
> of polymorphism as Neil's functions show (and better still Vincent's
> rewrites).

I think row types can give us that, and clean up other parts of the
numeric tower, too. That's something we've been thinking about for some
time.

Vincent