fixup! fixup! fixup! io-sim: Add support for unique symbol generation

Author: LSLeary

io-sim/src/Control/Monad/IOSim/CommonTypes.hs

@@ -207,9 +207,13 @@ ppLabelled pp Labelled { l_labelled = a, l_label = Just lbl } = concat ["Labelle
 -- | Abstract unique symbols à la "Data.Unique".
 newtype Unique s = MkUnique{ unMkUnique :: Integer }
   deriving stock   (Eq, Ord)
-  deriving newtype (Hashable, NFData)
+  deriving newtype NFData
 type role Unique nominal
 
+instance Hashable (Unique s) where
+  hash = fromInteger . unMkUnique
+  hashWithSalt = defaultHashWithSalt
+
 --
 -- Utils
 --

io-sim/src/Control/Monad/IOSim/Types.hs

@@ -105,6 +105,7 @@ import Control.Monad.Fail qualified as Fail
 import Data.Bifoldable
 import Data.Bifunctor (bimap)
 import Data.Dynamic (Dynamic, toDyn)
+import Data.Hashable (Hashable(hash))
 import Data.List.Trace qualified as Trace
 import Data.Map.Strict (Map)
 import Data.Maybe (fromMaybe)
@@ -632,7 +633,7 @@ instance MonadLabelledMVar (IOSim s) where
 instance MonadUnique (IOSim s) where
   type Unique (IOSim s) = Sim.Unique s
   newUnique  = IOSim (oneShot NewUnique)
-  hashUnique = fromInteger . unMkUnique
+  hashUnique = hash
 
 data Async s a = Async !IOSimThreadId (STM s (Either SomeException a))