When using `camlp4o -parser Camlp4ListComprehension' as preprocessor,
is the resulting code the naive translation, like in,

 [(x, y) | x <- xs, even xs, y <- ys]

=>

 List.flatten (
  List.map (fun x -> List.map (fun y -> (x, y)) ys) (List.filter even xs)
 )

or is there an optimization in order to avoid appends and minimize the
number of cons?

cheers

christian