【Haskell】MapをFunctor型クラスのインスタンスにする
import qualified Data.Map as Map class MyFunctor f where myFmap :: (a -> b) -> f a -> f b instance (Ord k) => MyFunctor (Map.Map k) where myFmap f = Map.fromList.map (\(k, v) -> (k, f v)).Map.toList
import qualified Data.Map as Map class MyFunctor f where myFmap :: (a -> b) -> f a -> f b instance (Ord k) => MyFunctor (Map.Map k) where myFmap f = Map.fromList.map (\(k, v) -> (k, f v)).Map.toList