I am probably not using Data.Vector the way it's intended, but it's the simplest data structure I found with O(n) random access.
Remember that vectors from Data.Vector are lazy arrays. Technically speaking they are arrays of pointers to lazily evaluated values. What you really want for graphics is most likely Data.Vector.Storable. A vector of that type is always fully evaluated and dense: import qualified Data.Vector as V import qualified Data.Vector.Storable as Vs import qualified Data.Vector.Unboxed as Vu import Data.Word v :: V.Vector Word64 v = V.fromList [1..1000] vs :: Vs.Vector Word64 vs = Vs.fromList [1..1000] vu :: Vu.Vector Word64 vu = Vu.fromList [1..1000] You would expect that a 1000-element array of `Word64` values takes exactly 8000 bytes of memory. This is true for `vs` and `vu`, but not for `v`, because it is a lazy array. The difference between storable and unboxed vectors is that the former has a certain address in memory that is not moved around. This is useful for example when you need to interface with OpenGL or SDL. Unboxed vectors can be faster in certain cases, but the difference is almost always negligible and would not be possible anyway if you were to interface with a non-Haskell library. Greets, Ertugrul