On Fri, 25 Jun 2010 18:30:06 -0300
Felipe Lessa <[email protected]> wrote:
> On Fri, Jun 25, 2010 at 12:41:48AM +0400, Alexey Khudyakov wrote:
> > Then constructor like one below arise naturally. And I don't know how to
> > write
> > them properly. It's possible to use fromList but then list could be
> > allocated
> > which is obviously wasteful.
>
> Did you see the generated core? I think you should give a try to
> the following simple code:
>
> import qualified Data.Vector.Generic as VG -- vector == 0.6.*
>
> vector2 :: Double -> Double -> Vec2D
> vector2 x y = Vec2D (VG.fromListN 2 [x,y])
>
I tryed to look at ghc core output but it was totally incomprehensible.
Is there any documentation about how to inspect and interpret generated
code, good practices etc?
> > Another question is there any specific problems with short vectors? They
> > could
> > be just 2 elements long. I mean performance problems
>
> Probably there will be more overhead than defining
>
> data Vec2D = Vec2D {-# UNPACK #-} !Double
> {-# UNPACK #-} !Double
>
> You should profile to see how much difference there is between
> those representations.
>
Sure. This price of code generality.
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