LamdaLisp (non-)example for failure of do notation

dofail.lisp

main =
(_mapSearchR 0 ([] ([] 0) ([] 1)) 0)

-- _mapSearchR :: Eq a => a -> [[a]] -> Int -> (Int, Int)
-- after removing the commented brackets this works too:
_mapSearchR =
(\ x xss k ->
  (IF (NIL xss)
      (: -1 -1)
      -- (
      { i <- (_listSearchR x (CAR xss) 0);
        (IF (<= 0 i)
            (: i k)
            (_mapSearchR x (CDR xss) (+ k 1))
        )
      }
      -- )
  )
)
-- this works:
-- (\ x xss k ->
--   (IF (NIL xss)
--       (: -1 -1)
--       ((\ i ->
--           (IF (<= 0 i)
--               (: i k)
--               (_mapSearchR x (CDR xss) (+ k 1))
--           )
--        ) (_listSearchR x (CAR xss) 0)
--       )
--   )
-- )

-- _listSearchR :: Eq a => a -> [a] -> Int -> Int
_listSearchR =
(\ x xs k ->
   (IF (NIL xs)
       -1
       (IF (== (CAR xs) x)
           k
           (_listSearchR x (CDR xs) (+ k 1))
       )
   )
)