module Lib.Ref2

import Prelude
import Lib.Common
import Lib.Types
import Data.IORef
import Data.SortedMap

data Defs : U where

-- St holds our code while we're optimizing
St : U
St = SortedMap QName Def

-- This is inspired by Idris.
-- Mainly to get an extra state variable into M
-- I tried parameterizing M, but inference was having trouble
-- in the existing code.
data Ref2 : (l : U) → U → U where
  MkRef : ∀ a . {0 x : U} → IORef a → Ref2 x a

getRef : ∀ io a. {{HasIO io}} → (l : U) → {{Ref2 l a}} → io a
getRef l {{MkRef a}} = readIORef a

modifyRef : ∀ io a. {{HasIO io}} → (l : U) → {{Ref2 l a}} → (a → a) → io Unit
-- TODO inference needs liftIO here
modifyRef l {{MkRef a}} f = liftIO $ modifyIORef a f