PLT-A4 IO Monad

Transcript

1. pineapple.cc ۚ୩Ұ࿕ʢ௕࡚େֶ৘ใσʔλՊֶ෦ʣ ʲิʳ*0Ϟφυ ϓϩάϥϛϯάݴޠ࿦
2. pineapple.cc Value Func Value’ x′  = fx
3. pineapple.cc Value Func Value’ Func3 Func2 Func1 • • x′  = (h ∙ g ∙ f)x
4. pineapple.cc x = (user input)
5. pineapple.cc toUpper :: Char -> Char x :: [Char] y :: [Char] x = “Hello, world.” y = map toUpper x
6. pineapple.cc x’ :: IO [Char] y’ :: IO [Char] x’ = getLine y’ = map toUpper x’ — ERROR!! toUpper :: Char -> Char x :: [Char] y :: [Char] x = “Hello, world.” y = map toUpper x
7. pineapple.cc x’ :: IO [Char] y’ :: IO [Char] x’ = getLine y’ = fmap (map toUpper) x’ toUpper :: Char -> Char x :: [Char] y :: [Char] x = “Hello, world.” y = map toUpper x
8. pineapple.cc x’ :: IO [Char] y’ :: IO [Char] x’ = getLine y’ = (toUpper <$>) <$> x’ toUpper :: Char -> Char x :: [Char] y :: [Char] x = “Hello, world.” y = toUpper <$> x ผղ
9. pineapple.cc Value Func Value’ Value Func Value’