From 18b3cfaf88d44ba6d2e1bfc27a3d43eb8381314b Mon Sep 17 00:00:00 2001
From: Evan Rutledge Borden <evan@evan-borden.com>
Date: Mon, 15 Jan 2018 16:02:14 -0500
Subject: [PATCH] Fix infix constructor pattern matching for normal
 constructors

Brittany was previously only support symbol based infix constructors. It
is common in some libraries (for example Esqueleto) to pattern match on
normal constructors as infix. Brittany was failing in this case by not
wrapping the constructor name in back ticks/spaces. Backticks and spaces
have been added in the case where the constructor contains any alpha
characters.
---
 src-literatetests/10-tests.blt                              | 3 +++
 src/Language/Haskell/Brittany/Internal/Layouters/Pattern.hs | 5 ++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/src-literatetests/10-tests.blt b/src-literatetests/10-tests.blt
index a3d8591..6659847 100644
--- a/src-literatetests/10-tests.blt
+++ b/src-literatetests/10-tests.blt
@@ -355,6 +355,9 @@ func (x:xr) = x
 #pending
 func (x:+:xr) = x
 
+#test normal infix constructor
+func (x `Foo` xr) = x
+
 
 ###############################################################################
 ###############################################################################
diff --git a/src/Language/Haskell/Brittany/Internal/Layouters/Pattern.hs b/src/Language/Haskell/Brittany/Internal/Layouters/Pattern.hs
index ebdd91d..2f881a0 100644
--- a/src/Language/Haskell/Brittany/Internal/Layouters/Pattern.hs
+++ b/src/Language/Haskell/Brittany/Internal/Layouters/Pattern.hs
@@ -13,6 +13,7 @@ where
 import           Language.Haskell.Brittany.Internal.Types
 import           Language.Haskell.Brittany.Internal.LayouterBasics
 
+import           Data.Char (isAlpha)
 import           RdrName ( RdrName(..) )
 import           GHC ( Located, runGhc, GenLocated(L), moduleNameString )
 import           HsSyn
@@ -80,7 +81,9 @@ layoutPat lpat@(L _ pat) = docWrapNode lpat $ case pat of
     let nameDoc = lrdrNameToText lname
     leftDoc  <- colsWrapPat =<< layoutPat left
     rightDoc <- colsWrapPat =<< layoutPat right
-    middle <- docLit nameDoc
+    middle <- docLit $ if Text.any isAlpha nameDoc
+      then Text.pack " `" <> nameDoc <> Text.pack "` "
+      else nameDoc
     return $ Seq.empty Seq.|> leftDoc Seq.|> middle Seq.|> rightDoc
   ConPatIn lname (RecCon (HsRecFields [] Nothing)) -> do
     -- Abc{} -> expr