a.hs

myFst :: (a, b) -> a
myFst x = fst x

myOdd :: Int -> Bool
myOdd x = odd x

-- (a) Ord is a typeclass. It means that the type supports the functions of the Ord typeclass (e.g. compare, <, > etc.). 
--     The type of qs mean that "a" belongs to typeclass "Ord". The function qs take a list of type "a" and return a list of type "a"
-- (b) The type of ++ is (++) :: [a] -> [a] -> [a]. It concatenates 2 lists.
-- (c) ys are the elements that are less or equal than x(the pivot of quicksort). zs are the elements that are greater than x.
-- (d) The function is quicksort.
-- (e)
qs :: Ord a => [a] -> [a]
qs a = case a of [] -> []
                 (x:xs) ->
                    let ys = [ y | y <- xs, y <= x ]
                        zs = [ z | z <- xs, x < z ]
                    in qs ys ++ [x] ++ qs zs

Well done.

type supports the functions of the Ord typeclass

To be precise, every instance of Ord has a total order given by compare.