mapM00.hs

import Control.Monad.State

-- 人
data Person = Person { name :: String  -- 名前
                     , age  :: Int     -- 年齢
                     } deriving Show 

-- グループ
data Group = Group [Person] deriving Show

g = Group []

-- グループに人を追加
addPerson              :: Person -> Group -> ((), Group)
addPerson p (Group ps) = ((), Group (ps++[p]))

addPs' (n,a) = State $ addPerson $ Person n a

addPs1 = mapM_ addPs' [("Tarou",10), ("Jirou",20), ("Hanko",30)]