Fresh: FreshIdT: rm newtype accessor

Author: Anton-Latukha

src/Nix/Fresh.hs

@@ -21,7 +21,7 @@ import           Control.Monad.Ref    ( MonadAtomicRef(..)
 import           Nix.Thunk
 
 --  2021-06-02: NOTE: Remove singleton newtype accessor in favour of free coerce
-newtype FreshIdT i m a = FreshIdT { unFreshIdT :: ReaderT (Ref m i) m a }
+newtype FreshIdT i m a = FreshIdT (ReaderT (Ref m i) m a)
   deriving
     ( Functor
     , Applicative
@@ -60,4 +60,4 @@ instance
     atomicModifyRef v (\i -> (succ i, i))
 
 runFreshIdT :: Functor m => Ref m i -> FreshIdT i m a -> m a
-runFreshIdT i m = runReaderT (unFreshIdT m) i
+runFreshIdT i m = runReaderT (coerce m) i