Jules Bean wrote:
Andrew Coppin wrote:
Andrew Coppin wrote:
copy :: Word32 -> IOUArray Word32 Bool -> Word32 -> IO (IOUArray Word32 Bool) copy p grid size = do let size' = size * p grid' <- newArray (1,size') False
mapM_ (\n -> do b <- readArray grid n if b then mapM_ (\x -> writeArray grid' (n + size*x) True) [0..p-1] else return () ) [1..size]
return grid'
Actually, thinking about this... for most kinds of arrays (whether boxed or unboxed, mutable or immutable) there's probably a more efficient way to copy the data then this. Maybe we should add something to the various array APIs to allow efficient copying of arrays / large chunks of arrays?
Ideally we'd have the compiler generate optimal code anyway, then you wouldn't need such things.
So, let's hope those compiler/optimiser guys keep working hard!
True - but "copyArray x y" is surely a lot clearer than some longwinded mapM thing, no? ;-)