chapter18.hs

module Lib where

-- 18.7 Question 1

data Nope a = NopeDotJpg deriving (Eq, Show)

instance Functor Nope where
  fmap _ NopeDotJpg = NopeDotJpg

instance Applicative Nope where
  pure _  = NopeDotJpg
  _ <*> _ = NopeDotJpg

instance Monad Nope where
  return _ = NopeDotJpg
  _ >>= _  = NopeDotJpg


-- Question 2

data PhhhbbtttEither b a = Left' a | Right' b deriving (Eq, Show)

instance Functor (PhhhbbtttEither x) where
  fmap f (Left' a)  = Left' (f a)
  fmap _ (Right' b) = Right' b

instance Applicative (PhhhbbtttEither b) where
  pure a  = Left' a
  Right' e <*> _ = Right' e
  Left'  f <*> a = fmap f a

instance Monad (PhhhbbtttEither b) where
  return = pure
  Left'  l >>= f = f l 
  Right' r >>= _ = Right' r