[clean-list] Efficient unboxed 2D array creation

[Shivkumar Chandrasekaran]

Hi,

I am looking for an efficient version to create unboxed 2D arrays (of 
Real and Complex types). The usual approach:

createUnboxedRealArr2D :: !Int !Int !Real -> !*{#*{#Real}}
createUnboxedRealArr2D m n x = {createUnboxedRealArr n x \\ i <- r}
where
	r = [0..m-1]

seems to be pathetically slow. I seem to recall this being discussed on 
this list once before. I looked at htoclean to see if I can use C 
somehow. But unfortunately that does not seem to be possible as htoclean 
does not support arrays. I did notice the documentation mentioning 
something about the ccall ABC instruction supporting arrays, but I 
couldn't figure out how to use it. There does not seem to be anything in 
StdEnv and StdLib of any use either (createArray_u does not seem to have 
the appropriate instance).

Can someone please tell me how to do this efficiently? I hate to fake 2D 
arrays with 1D arrays. Thanks,

--shiv--

PS: m and n are fairly large for me (in the 100s).