teivah

plusOne :: Maybe (Int -> Int)
plusOne = Just (+ 1)

teivah

plusOne :: Int -> Maybe Int
plusOne x = Just (x + 1)

teivah

plusOne :: Int -> Int
plusOne x = x + 1

teivah

withMonad :: Int -> String -> Maybe String
withMonad age name = do
  validateAge age
  s <- return (greet name)
  return (greet s) -- Just "Hello Hello John"

teivah

withMonad :: Int -> String -> Maybe String
withMonad age name = do
  validateAge age
  return (greet name)

teivah

withMonad :: Int -> String -> Maybe String
withMonad age name = validateAge age >>= \_ -> return (greet name)

teivah

withApplicative :: Int -> String -> Maybe String
withApplicative age name = greet <$> (Just name) <*> validateAge age

teivah

validateAge :: Int -> Maybe Int
validateAge age
  | age >= 18 = return age
  | otherwise = Nothing

greet :: String -> String
greet name = "Hello " ++ name

teivah

divide :: Float -> Float -> Maybe Float
divide _ 0 = Nothing
divide x y = return (x / y)

teivah

plusOne :: Int -> Maybe Int
plusOne x = return (x + 1)

monadEx :: Maybe Int
monadEx = Just 42 >>= plusOne -- Just 43