[Haskell-cafe] Array copying

[Jules Bean]

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!

Jules