Sharing map (cleaned-up Core listing)

SharingMap.hs

sharingMap1 :: [([a], a, Maybe a)] -> (# Bool, [a] #)
sharingMap1 [] = (# False, [] #);
sharingMap1 ((ds_diz, y1_adI, Nothing):ys) =
            let (# ww1_skq, ww2_skr #) = sharingMap1 ys
            in case ww1_skq of {
              False -> (# False, ds_diz #);
              True -> (# True, (y1_adI:ww2_skr) #)
            }
sharingMap1 ((ds_diz, y1_adI, Just y2):ys) =
            let (# ww1_skq, ww2_skr #) = sharingMap1 ys
            in (# True, (y2:ww2_skr) #)


sharingMap :: (a -> Maybe a) -> [a] -> Maybe [a]
sharingMap f xs =
    case sharingMap1 (zip3 (tails xs) xs (map f xs))
    of _ { (# m, ww2_skr #) ->
    case m of _ {
      False -> Nothing
      True -> Just ww2_skr
    }
    }