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

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

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

teivah

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

teivah

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

teivah

fmapEx :: Maybe Int -- A function returning a Maybe Int
fmapEx = fmap (+ 1) (Just 42) -- Just 43

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)