MonadVar
class MonadNew m v
class MonadLock m v
class MonadRead m v
class MonadWrite m v
class MonadSwap m v
class MonadMutate_ m v
class MonadMutate m v
class MonadFoldMutate m v
class MonadMutateM_ f m v
class MonadMutateM f m v
class MonadFoldMutateM m n v