Haskell: Pattern Matching Deconstructor Assignment (Within Functions)

let_case_where.hs

tuple1 a b = (a, b)
tuple2 a b = (b, a)

-- recursive let
func1 n = 
    let 
        (a, b) = tuple1 3 n
        (_, y) = tuple2 a b
    in 
        a + b + y

-- nested let
func2 n = 
    let 
        (a, b) = tuple1 3 n
    in 
        let 
            (_, y) = tuple2 a b
        in 
            a + b + y

-- nested case
func3 n =
    case tuple1 3 n of
        (a, b) -> case tuple2 a b of
            (_, y) -> a + b + y

-- where
func4 n = 
        a + b + y
    where 
        (a, b) = tuple1 3 n
        (_, y) = tuple2 a b

main = do
    print.show $ func1 1
    print.show $ func2 1
    print.show $ func3 1
    print.show $ func4 1