From 8787814bd92ad7d97fdf89a396ad292d2c97ab7a Mon Sep 17 00:00:00 2001
From: Dmitry Astapov <dastapov@gmail.com>
Date: Wed, 11 Apr 2018 13:25:50 +0100
Subject: [PATCH 1/3] Fix: parens around lists in local opens

---
 src/Fmt_ast.ml | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/Fmt_ast.ml b/src/Fmt_ast.ml
index 13b34c84f1..51e492c388 100644
--- a/src/Fmt_ast.ml
+++ b/src/Fmt_ast.ml
@@ -1375,7 +1375,10 @@ and fmt_expression c ?(box= true) ?epi ?eol ?parens ?ext
         match e0.pexp_desc with
         | Pexp_array _ | Pexp_constraint _ | Pexp_record _ | Pexp_tuple _ ->
             (".", "")
-        | _ -> (".(", ")")
+        | _ ->
+          match sugar_list_exp e0 with
+          | Some _ -> (".", "")
+          | None   -> (".(", ")")
       in
       hvbox 0
         ( fits_breaks_if parens "" "("

From 6535cd8d9aa2a9d9ccf5705baf79cfe8a46fdb8a Mon Sep 17 00:00:00 2001
From: Dmitry Astapov <dastapov@gmail.com>
Date: Thu, 12 Apr 2018 13:27:12 +0100
Subject: [PATCH 2/3] Fix: do not put parens around patterns enclosed in list

---
 src/Ast.ml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/Ast.ml b/src/Ast.ml
index 9b876c9ca4..ed4affeb0b 100644
--- a/src/Ast.ml
+++ b/src/Ast.ml
@@ -761,6 +761,12 @@ end = struct
       , Ppat_construct ({txt= Lident "::"}, _) )
       when tl == pat ->
         false
+    | ( Pat
+          { ppat_desc=
+              Ppat_construct
+                ({txt= Lident "::"}, Some {ppat_desc= Ppat_tuple [_; _]}) }
+      , (Ppat_construct _| Ppat_variant _) ) ->
+        false
     | ( Pat
           { ppat_desc=
               Ppat_construct

From b4675964db2212dbfa7073c2fe3cbd077e5314c9 Mon Sep 17 00:00:00 2001
From: Dmitry Astapov <dastapov@gmail.com>
Date: Thu, 12 Apr 2018 16:43:22 +0100
Subject: [PATCH 3/3] Fix: parens in record update where defaul val is trivial

---
 src/Ast.ml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/Ast.ml b/src/Ast.ml
index ed4affeb0b..d70354709c 100644
--- a/src/Ast.ml
+++ b/src/Ast.ml
@@ -937,6 +937,9 @@ end = struct
       | Pexp_record (flds, _)
         when List.exists flds ~f:(fun (_, e0) -> e0 == exp) ->
           exposed Non_apply exp (* Non_apply is perhaps pessimistic *)
+      | Pexp_record (_, Some ({pexp_desc= Pexp_apply ({pexp_desc= Pexp_ident {txt= Lident i}},_) } as e0))
+        when e0 == exp && is_prefix_id i ->
+          false
       | Pexp_record (_, Some ({pexp_desc= Pexp_apply _} as e0))
         when e0 == exp ->
           true