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])
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. Cheers, -- Felipe.