On Sun, Jul 15, 2012 at 06:51:07PM +0100, Tsuyoshi Ito wrote:
Thank you for the response. This sounds exciting, but sadly, I must admit that it is a little (?) above my head, and I cannot relate this extension to my original question….
Sorry about that -- I got a bit side-tracked. The combinator you wanted to use was repeat :: Int -> (Int -> MyArr e a) -> MyArr e a That won't be possible, but with this extension you could use repeat' :: Int -> StaticArrow ((->) Int) MyArr e a -> MyArr e a The definition of StaticArrow (in the arrows package) is a wrapper newtype StaticArrow f a b c = StaticArrow (f (a b c)) so StaticArrow ((->) Int) MyArr e a ~= Int -> MyArr e a. Now you could write test2 :: MyArr [Double] String test2 = proc xs -> do let y = func1 xs z <- job1 -< xs (|(repeat' 100) (StaticArrow (\i -> job3 (i * 2)) -< xs !! y + z)|) which isn't quite what you wanted, because i wouldn't be in the environment, but we could put it there as you did in your original post, or something like test2 :: MyArr [Double] String test2 = proc xs -> do let y = func1 xs z <- job1 -< xs (|(repeat' 100) (do i <- StaticArrow (arr . const) -< () StaticArrow (\i -> job3 (i * 2)) -< xs !! i + y + z)|) I did say it would be clunky, but at least there's no dumping the tuple and picking it up again.