Eff.Choose + Eff.State + Lens

gistfile1.hs

{-# LANGUAGE FlexibleContexts, ScopedTypeVariables #-}
{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses, UndecidableInstances #-}
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE TemplateHaskell #-}

module Main where
import Data.Typeable
import Control.Eff
import Control.Eff.State.Lazy as EST
import Control.Eff.Choose
import Control.Monad.State.Class (MonadState(..))
import Control.Lens

instance (Typeable x, Member (State x) r) => MonadState x (Eff r) where
  get = EST.get 
  put = EST.put 

----

data Foo = Foo
  { _hoge :: Int
  , _piyo :: String
  , _fuga :: Bool
  } deriving (Show, Typeable)

makeLenses ''Foo

proc :: (Member Choose r, Member (State Foo) r) => Eff r Foo
proc = do
  hoge *= 2
  s <- choose ["+++", "---", "***"]
  p <- use $ piyo
  piyo .= s ++ p ++ s
  fuga .= True 

  (res :: Foo) <- EST.get
  return res

----

main = do
   let foo = Foo
               { _hoge = 100
               , _piyo = "Hello"
               , _fuga = False
               }
   print . run $ runChoice (execState foo proc)

-- 実行結果
-- [ Foo {_hoge = 200, _piyo = "+++Hello+++", _fuga = True}
-- , Foo {_hoge = 200, _piyo = "---Hello---", _fuga = True}
-- , Foo {_hoge = 200, _piyo = "***Hello***", _fuga = True}]