From 71157dbd4e34191441c67dc0c472be4c6f0bb499 Mon Sep 17 00:00:00 2001
From: Markus Westerlind <marwes91@gmail.com>
Date: Fri, 1 Dec 2017 19:10:26 +0100
Subject: [PATCH] feat(format): Format do expressions

---
 format/src/pretty_print.rs   | 18 +++++++++++++++++-
 format/tests/pretty_print.rs | 10 ++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/format/src/pretty_print.rs b/format/src/pretty_print.rs
index 46d6b05905..fd4e78dea6 100644
--- a/format/src/pretty_print.rs
+++ b/format/src/pretty_print.rs
@@ -3,7 +3,7 @@ use std::{iter, ops};
 use itertools::{Either, Itertools};
 use pretty::{Arena, DocAllocator, DocBuilder};
 
-use base::ast::{Expr, Pattern, SpannedExpr, SpannedPattern, ValueBinding};
+use base::ast::{Do, Expr, Pattern, SpannedExpr, SpannedPattern, ValueBinding};
 use base::kind::Kind;
 use base::pos::{self, BytePos, HasSpan, Span, Spanned};
 use base::source;
@@ -288,6 +288,22 @@ impl<'a: 'e, 'e> Printer<'a, 'e> {
                     self.pretty_expr_(binds.last().unwrap().alias.span.end, body)
                 ].group()
                 }
+                Expr::Do(Do {
+                    ref id,
+                    ref bound,
+                    ref body,
+                    ..
+                }) => chain![arena;
+                        chain![arena;
+                            "do",
+                            self.space_before(id.span.start),
+                            id.value.name.as_ref(),
+                            self.space_after(id.span.end),
+                            "=",
+                            self.hang(arena.nil(), bound).group()
+                        ].group(),
+                        self.pretty_expr_(bound.span.end, body)
+                    ],
                 Expr::Error(_) => arena.text("<error>"),
             };
         comments.append(doc)
diff --git a/format/tests/pretty_print.rs b/format/tests/pretty_print.rs
index 97fb3ecced..9d17f8d120 100644
--- a/format/tests/pretty_print.rs
+++ b/format/tests/pretty_print.rs
@@ -300,3 +300,13 @@ let semigroup =
 "#;
     assert_diff!(&format_expr(expr).unwrap(), expr, " ", 0);
 }
+
+#[test]
+fn do_expression() {
+    let expr = r#"
+do /* x1 */ x /* x2 */ = Some 1
+// test
+test abc 1232 ""
+"#;
+    assert_diff!(&format_expr(expr).unwrap(), expr, " ", 0);
+}