A GADT version seems to generate OK code:
data Top
data NTop
data Rope t where
Empty :: Rope Top
Leaf :: Rope NTop
Node :: !(Rope NTop) -> !(Rope NTop) -> Rope NTop
index :: Rope t -> Int -> Word8
index Empty _ = error "empty"
index Leaf _ = error "leaf"
index (Node l r) n = index' l n
where
index' :: Rope NTop -> Int -> Word8
index' Leaf _ = error "leaf"
index' (Node l r) n = index' l n
Here's the result of -O -ddump-simpl for index':
$windex'_rx5 =
\ (w_swu :: Tree.Rope Tree.NTop) ->
case w_swu of wild_Xf {
Tree.Leaf -> lvl1_rwZ; Tree.Node l_adF r_adG -> $windex'_rx5 l_adF
}
Regards,
Zun.
_______________________________________________
Haskell-Cafe mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/haskell-cafe
