From b03f989f364c174b65ef34dcf1e3d52e1d3a89d3 Mon Sep 17 00:00:00 2001
From: Vladislav Zavialov <vlad.z.4096@gmail.com>
Date: Fri, 12 Jul 2019 12:38:42 +0300
Subject: [PATCH] Bang patterns and splices in lambdas

---
 .../declaration/value/function/lambda-single-line-out.hs | 6 ++++++
 .../declaration/value/function/lambda-single-line.hs     | 6 ++++++
 src/Ormolu/Printer/Meat/Declaration/Value.hs             | 9 ++++++---
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/data/examples/declaration/value/function/lambda-single-line-out.hs b/data/examples/declaration/value/function/lambda-single-line-out.hs
index 7c67204..e60799d 100644
--- a/data/examples/declaration/value/function/lambda-single-line-out.hs
+++ b/data/examples/declaration/value/function/lambda-single-line-out.hs
@@ -7,3 +7,9 @@ bar x =
 
 baz :: a -> a -> a
 baz = \ ~x ~y -> x
+
+zag :: a -> a -> a
+zag = \ !x !y -> x
+
+spl :: a -> a
+spl = \ $([p|x|]) -> x
diff --git a/data/examples/declaration/value/function/lambda-single-line.hs b/data/examples/declaration/value/function/lambda-single-line.hs
index 87ffc1f..025d63d 100644
--- a/data/examples/declaration/value/function/lambda-single-line.hs
+++ b/data/examples/declaration/value/function/lambda-single-line.hs
@@ -7,3 +7,9 @@ bar x =
 
 baz :: a -> a -> a
 baz = \ ~x  ~y -> x
+
+zag :: a -> a -> a
+zag = \ !x  !y -> x
+
+spl :: a -> a
+spl = \ $([p|x|]) -> x
diff --git a/src/Ormolu/Printer/Meat/Declaration/Value.hs b/src/Ormolu/Printer/Meat/Declaration/Value.hs
index 67b7b14..c486222 100644
--- a/src/Ormolu/Printer/Meat/Declaration/Value.hs
+++ b/src/Ormolu/Printer/Meat/Declaration/Value.hs
@@ -135,9 +135,12 @@ p_match' placer pretty style isInfix m_pats m_grhss = do
           PatternBind -> stdCase
           Case -> stdCase
           Lambda -> do
-            case unLoc (NE.head ne_pats) of
-              LazyPat _ _ -> txt "\\ "
-              _ -> txt "\\"
+            let needsSpace = case unLoc (NE.head ne_pats) of
+                  LazyPat _ _ -> True
+                  BangPat _ _ -> True
+                  SplicePat _ _ -> True
+                  _ -> False
+            txt (if needsSpace then "\\ " else "\\")
             stdCase
           LambdaCase -> stdCase
       return inci'