Hello Grzegorz, Wednesday, September 23, 2009, 7:19:59 PM, you wrote:
This seems like a bug in the implementation of writeArray: when passed let (l,u) = ((0,10),(20,20))
writeArray computes raw index (from 0 to total number of array elements) and check that this index is correct. with multi-dimensional arrays this approach may lead to wrong results, as you mentioned. it's known problem that isn't fixed for a long time probably due to efficiency cautions. the error is here: data Ix i => Array i e = Array !i -- the lower bound, l !i -- the upper bound, u !Int -- a cache of (rangeSize (l,u)) -- used to make sure an index is -- really in range (Array# e) -- The actual elements (!) :: Ix i => Array i e -> i -> e arr@(Array l u n _) ! i = unsafeAt arr $ safeIndex (l,u) n i safeIndex :: Ix i => (i, i) -> Int -> i -> Int safeIndex (l,u) n i = let i' = unsafeIndex (l,u) i in if (0 <= i') && (i' < n) then i' else error "Error in array index" obviously, safeIndex should use inRange call instead -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com