[Haskell-beginners] basic use of Applicative

[Imants Cekusins]

module BasicApplicative where


-- 2 arg
upd2:: Int -> Int -> Int
upd2 x1 x2 = x1 * x2

-- 3 arg
upd3:: Int -> Int -> Int -> Int
upd3 x1 x2 x3 = x1 * x2 + x3


-- pure
pureMaybe::Int -> Maybe Int
pureMaybe = pure

pureList::Int -> [Int]
pureList = pure


-- maybe
maybe2::Maybe Int -> Maybe Int -> Maybe Int
maybe2 mi1 mi2 = upd2 <$> mi1 <*> mi2


-- list
list2::[Int] -> [Int] -> [Int]
list2 l1 l2 = upd2 <$> l1 <*> l2

-- same result as list2
list2p::[Int] -> [Int] -> [Int]
list2p l1 l2 = pure upd2 <*> l1 <*> l2


list3::[Int] -> [Int] -> [Int] -> [Int]
list3 l1 l2 l3 = upd3 <$> l1 <*> l2 <*> l3