Add instance ann ~ Void => Pretty (Doc ann) (#234)

When there are no annotations, Doc is Pretty.
quchen · Apr 26, 2024 · eccc839 · eccc839
1 parent 7e32c01
commit eccc839
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/prettyprinter/src/Prettyprinter/Internal.hs b/prettyprinter/src/Prettyprinter/Internal.hs
@@ -3,6 +3,7 @@
 {-# LANGUAGE DefaultSignatures   #-}
 {-# LANGUAGE DeriveDataTypeable  #-}
 {-# LANGUAGE DeriveGeneric       #-}
+{-# LANGUAGE GADTs               #-}
 {-# LANGUAGE OverloadedStrings   #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 
@@ -292,6 +293,9 @@ class Pretty a where
 --   , (1, [2, 2, 2, 2, 2, 2, 2, 2])
 --   , (1, [2, 2, 2, 2, 2, 2, 2, 2]) ] ]
 
+instance ann ~ Void => Pretty (Doc ann) where
+  pretty = vacuous
+
 instance Pretty a => Pretty (Const a b) where
   pretty = pretty . getConst