{-# LANGUAGE AllowAmbiguousTypes #-}

-- This Source Code Form is subject to the terms of the Mozilla Public
-- License, v. 2.0. If a copy of the MPL was not distributed with this
-- file, You can obtain one at https://mozilla.org/MPL/2.0/.

{- |
Copyright   :  (c) 2023 Yamada Ryo
License     :  MPL-2.0 (see the file LICENSE)
Maintainer  :  ymdfield@outlook.jp
Stability   :  experimental
Portability :  portable
-}
module Data.Effect.State where

data State s a where
    Get :: State s s
    Put :: s -> State s ()

makeEffectF [''State]

gets :: (State s <: f, Functor f) => (s -> a) -> f a
gets :: forall s (f :: * -> *) a.
(State s <: f, Functor f) =>
(s -> a) -> f a
gets s -> a
f = s -> a
f forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> forall s (f :: * -> *). SendIns (State s) f => f s
get

modify :: (State s <: m, Monad m) => (s -> s) -> m ()
modify :: forall s (m :: * -> *). (State s <: m, Monad m) => (s -> s) -> m ()
modify s -> s
f = forall s (f :: * -> *). SendIns (State s) f => s -> f ()
put forall b c a. (b -> c) -> (a -> b) -> a -> c
. s -> s
f forall (m :: * -> *) a b. Monad m => (a -> m b) -> m a -> m b
=<< forall s (f :: * -> *). SendIns (State s) f => f s
get