Implement `IndentPolicyLeft` for one HsApp case

src/Language/Haskell/Brittany/Internal/Layouters/Expr.hs

@@ -32,6 +32,11 @@ import           Language.Haskell.Brittany.Internal.Layouters.Type
 
 layoutExpr :: ToBriDoc HsExpr
 layoutExpr lexpr@(L _ expr) = do
+  indentPolicy <- mAsk
+    <&> _conf_layout
+    .>  _lconfig_indentPolicy
+    .>  confUnpack
+  let allowFreeIndent = indentPolicy == IndentPolicyFree
   docWrapNode lexpr $ case expr of
     HsVar vname -> do
       docLit =<< lrdrNameToTextAnn vname
@@ -114,42 +119,50 @@ layoutExpr lexpr@(L _ expr) = do
       let (headE, paramEs) = gather [exp2] exp1
       headDoc <- docSharedWrapper layoutExpr headE
       paramDocs <- docSharedWrapper layoutExpr `mapM` paramEs
-      docAlt
+      docAltFilter
         [ -- foo x y
-          docCols ColApp
+          ( True
+          , docCols ColApp
           $ appSep (docForceSingleline headDoc)
           : spacifyDocs (docForceSingleline <$> paramDocs)
+          )
         , -- foo x
           --     y
-          docSeq
+          ( allowFreeIndent
+          , docSeq
             [ appSep (docForceSingleline headDoc)
             , docSetBaseY
             $ docAddBaseY BrIndentRegular
             $ docLines
             $ (docForceSingleline <$> paramDocs)
             ]
+          )
         , -- foo
           --   x
           --   y
-          docSetParSpacing
+          ( True
+          , docSetParSpacing
           $ docAddBaseY BrIndentRegular
           $ docPar
             (docForceSingleline headDoc)
             ( docNonBottomSpacing
             $ docLines paramDocs
             )
+          )
         , -- ( multi
           --   line
           --   function
           -- )
           --   x
           --   y
-          docAddBaseY BrIndentRegular
+          ( True
+          , docAddBaseY BrIndentRegular
           $ docPar
             headDoc
             ( docNonBottomSpacing
             $ docLines paramDocs
             )
+          )
         ]
     HsApp exp1 exp2 -> do
       -- TODO: if expDoc1 is some literal, we may want to create a docCols here.