Re: [reactive] Bounce

Shouldn't Reactive also have VectorSpace instances for Behaviors of VectorSpace elements? So that the code becomes

positionB x0 v t = pure x0 ^+^ v ^* t

Maybe it already has, in that case, sorry for the spam ;) On Fri, Nov 21, 2008 at 7:00 PM, Greg Fitzgerald wrote:

...

...

...

positionB :: Double -> Behavior Double -> Behavior Double -> Behavior Double positionB x0 v t = (x0 +) <$> liftA2 (*) v t positionB x0 v t = pure x0 + v * t

That's very convenient. I'm showing this stuff off to visual designers, so tricks like this have great Sales appeal. :)

If others are trying this out, the Num instance is implemented in FRP.Reactive.Num.

-Greg

...

For that matter, you can also say, thanks to Num overloading:

positionB :: Double -> Behavior Double -> Behavior Double -> Behavior Double positionB x0 v t = pure x0 + v * t

Sadly, similar convenience does not come for free with non-methods, such as most of the FieldTrip API. For non-methods, in the past (with Fran), I've written parallel sets of modules with behavior-lifted functionality. It's tedious to set up but convenient to use. Perhaps a tool could automate

On Fri, Nov 21, 2008 at 6:48 AM, Conal Elliott wrote: the

...

job.

By the way, a nice feature of Yampa is that it avoids this lifting business altogether, via desugaring for the arrow notation.

- Conal

On Fri, Nov 21, 2008 at 12:14 AM, Thomas Davie wrote:

...

...

positionB :: Double -> Behavior Double -> Behavior Double -> Behavior Double positionB x0 v t = (x0 +) <$> liftA2 (*) v t

On an unrelated note, I created a package called InfixApplicative, because I found that exactly this kind of expression looked ugly in my code. If you import it, you can define this instead:

positionB x0 v t = (x0 +) <$> (v <^(*)^> t)

Hope that helps

Bob _______________________________________________ Reactive mailing list Reactive@haskell.org http://www.haskell.org/mailman/listinfo/reactive

_______________________________________________ Reactive mailing list Reactive@haskell.org http://www.haskell.org/mailman/listinfo/reactive