*when I said type-safe, I actually meant type-stable as Tim was discussing
On Monday, July 6, 2015 at 7:48:23 PM UTC-4, Tom Breloff wrote: > > Yes for the general behavior I had in mind it would be nearly impossible > to keep the view constructor type-safe. For certain uses, that's less > important than keeping the subsequent operations fast and type-safe, but > that may be a very steep hill to climb. > > As I'm thinking about the problem a little more, it might be very hard to > have a good general solution, but maybe I could implement some small > problem-specific methods that are fast for a limited purpose. There are 2 > examples that come to mind in OnlineStats: extending a vector/matrix > representing the X from a regression with a scalar/vector of ones for the > bias term, and concatenating an X and Y to pass through the sweep > operation. It would be nice if there was a low-overhead way to do that > without needing to re-write the math. Another use I have in mind is for > VAR/VECM impact analysis, where there is a large matrix with dense upper > and sparse lower... it would be nice to abstract that away. These are > actually very different problems, and it's probably too ambitious to have > good solutions for both at the same time. > > Long story short, I might continue to work on some problem specific > solutions in a semi-reusable way... I'll post here if I think they could be > useful to anyone else. If anyone looks at Blox.jl and thinks I should NOT > abandon what I was doing, please let me know. :) > > On Monday, July 6, 2015 at 2:02:04 PM UTC-4, Tim Holy wrote: >> >> On Monday, July 06, 2015 10:59:48 AM Tom Breloff wrote: >> > I plan on adding "views" to this as well, which will probably just >> check to >> > see if the indices are contained within a sub-array to return an >> > ArrayViews::view, otherwise a light wrapper around a "BlockView" >> >> You're not going to be able to do that in a type-stable way, because it's >> something that depends on the values of the indexes rather than their >> type. >> >> --Tim >> >>
