GADT confusion

Hi all I am working on D836 and have the following test case data MaybeDefault v where SetTo4 :: forall v a. (( Eq v, Show v ) => v -> MaybeDefault v -> a -> MaybeDefault [a]) GHC 7.10.1 regards the return type of SetTo4 as `MaybeDefault [a]` The question is, due to the parens, is the return type not the whole RHS? i.e. Similar to how in the signature map :: (a -> b) -> [a] -> [b] the first paramater is a single function. I am sure I am just confused here. Alan