Add instance for Show1 for Annotation and NExprF

Nix/Expr/Types.hs

@@ -13,6 +13,7 @@ import           Control.Monad hiding (forM_, mapM, sequence)
 import           Data.Data
 import           Data.Fix
 import           Data.Foldable
+import           Data.Functor.Classes (Show1(..))
 import           Data.Map (Map)
 import           Data.Text (Text, pack)
 import           Data.Traversable
@@ -71,6 +72,9 @@ data NExprF r
   -- ^ Assert that the first returns true before evaluating the second.
   deriving (Ord, Eq, Generic, Typeable, Data, Functor, Show)
 
+instance Show1 NExprF where
+  showsPrec1 = showsPrec
+
 -- | We make an `IsString` for expressions, where the string is interpreted
 -- as an identifier. This is the most common use-case...
 instance IsString NExpr where

Nix/Expr/Types/Annotated.hs

@@ -13,6 +13,7 @@ import           Control.Monad        hiding (forM_, mapM, sequence)
 import           Data.Data
 import           Data.Fix
 import           Data.Function        (on)
+import           Data.Functor.Classes (Show1(..))
 import           Data.Functor.Compose
 import           Data.Semigroup
 import           GHC.Generics
@@ -36,6 +37,9 @@ data Ann ann a = Ann{ annotation :: ann
                     }
   deriving (Ord, Eq, Data, Generic, Functor, Read, Show)
 
+instance Show ann => Show1 (Ann ann) where
+  showsPrec1 = showsPrec
+
 instance Semigroup SrcSpan where
   s1 <> s2 = SrcSpan ((min `on` spanBegin) s1 s2)
                      ((max `on` spanEnd) s1 s2)