Fix not pretty-printing unboxed tuples correctly

CHANGELOG.md

@@ -19,6 +19,7 @@
 - Fix the bug of wrongly converting a `newtype` instance to a `data` one ([#839])
 - Fix the bug of not pretty-printing multiple functional dependencies in a typeclass ([#843])
 - Fix the bug of not pretty-printing data declarations with records and typeclass constraints ([#849])
+- Fix the bug of not pretty-printing unboxed tuples ([#868])
 
 ### Removed
 
@@ -374,6 +375,7 @@ This version is accidentally pushlished, and is the same as 5.3.3.
 [@uhbif19]: https://github.com/uhbif19
 [@toku-sa-n]: https://github.com/toku-sa-n
 
+[#868]: https://github.com/mihaimaruseac/hindent/pull/868
 [#849]: https://github.com/mihaimaruseac/hindent/pull/849
 [#843]: https://github.com/mihaimaruseac/hindent/pull/843
 [#839]: https://github.com/mihaimaruseac/hindent/pull/839

TESTS.md

@@ -2831,6 +2831,17 @@ Unboxed `String`
 a = "Foo"#
 ```
 
+`UnboxedTuple`
+
+```haskell
+{-# LANGUAGE UnboxedTuples #-}
+
+f :: (# Int, Int #) -> (# Int, Int #)
+f t =
+  case t of
+    (# x, y #) -> (# x, y #)
+```
+
 `NumericUnderscores`
 
 ```haskell

src/HIndent/Pretty.hs

@@ -58,7 +58,7 @@
 import qualified Language.Haskell.GhclibParserEx.GHC.Hs.Expr as GHC
 import Text.Show.Unicode
 #if MIN_VERSION_ghc_lib_parser(9,6,1)
 import qualified Data.Foldable as NonEmpty
 import qualified GHC.Core.DataCon as GHC
 #endif
 #if !MIN_VERSION_ghc_lib_parser(9,6,1)
@@ -244,15 +244,23 @@
 #endif
 prettyHsExpr (GHC.SectionL _ l o) = spaced [pretty l, pretty (InfixExpr o)]
 prettyHsExpr (GHC.SectionR _ o r) = (pretty (InfixExpr o) >> space) |=> pretty r
-prettyHsExpr (GHC.ExplicitTuple _ full _) = horizontal <-|> vertical
+prettyHsExpr (GHC.ExplicitTuple _ full boxity) = horizontal <-|> vertical
   where
-    horizontal = hTuple $ fmap pretty full
+    horizontal = parH $ fmap pretty full
     vertical =
-      parens
+      parV
         $ prefixedLined ","
         $ fmap (\e -> unless (isMissing e) (space |=> pretty e)) full
     isMissing GHC.Missing {} = True
     isMissing _ = False
+    parH =
+      case boxity of
+        GHC.Boxed -> hTuple
+        GHC.Unboxed -> hUnboxedTuple
+    parV =
+      case boxity of
+        GHC.Boxed -> parens
+        GHC.Unboxed -> unboxedParens
 prettyHsExpr (GHC.ExplicitSum _ position numElem expr) = do
   string "(#"
   forM_ [1 .. numElem] $ \idx -> do
@@ -540,7 +548,7 @@
 prettyMatchExpr GHC.Match {m_ctxt = GHC.LambdaExpr, ..} = do
   string "\\"
   unless (null m_pats)
     $ case GHC.unLoc $ head m_pats of
         GHC.LazyPat {} -> space
         GHC.BangPat {} -> space
         _ -> return ()
@@ -579,7 +587,7 @@
 prettyMatchProc GHC.Match {m_ctxt = GHC.LambdaExpr, ..} = do
   string "\\"
   unless (null m_pats)
     $ case GHC.unLoc $ head m_pats of
         GHC.LazyPat {} -> space
         GHC.BangPat {} -> space
         _ -> return ()
@@ -1223,7 +1231,7 @@
   pretty' (GHC.DctMulti _ ts) = hvTuple $ fmap pretty ts
 
 instance Pretty GHC.OverlapMode where
   pretty' GHC.NoOverlap {} = notUsedInParsedStage
   pretty' GHC.Overlappable {} = string "{-# OVERLAPPABLE #-}"
   pretty' GHC.Overlapping {} = string "{-# OVERLAPPING #-}"
   pretty' GHC.Overlaps {} = string "{-# OVERLAPS #-}"
@@ -1344,8 +1352,8 @@
       [] -> pure ()
       [x'] -> string x'
       xs -> do
         string $ head xs
         indentedWithFixedLevel 0 $ newlinePrefixed $ string <$> tail xs
   pretty' (GHC.IEModuleContents _ name) =
     pretty $ fmap ModuleNameWithPrefix name
   pretty' GHC.IEGroup {} = docNode
@@ -1697,7 +1705,7 @@
   pretty' (GHC.HsFloatPrim _ x) = pretty x >> string "#"
   pretty' GHC.HsDoublePrim {} = notUsedInParsedStage
   pretty' x =
     case x of
       GHC.HsString {} -> prettyString
       GHC.HsStringPrim {} -> prettyString
     where
@@ -1829,7 +1837,7 @@
           string p |=> pretty (fmap StmtLRInsideVerticalList x)
           newline
         string "]"
       stmtsAndPrefixes l = ("| ", head l) : fmap (", ", ) (tail l)
 
 instance Pretty DoExpression where
   pretty' DoExpression {..} = do