---

yaml
---
r: 210687
b: refs/heads/try
c: f59f41e
h: refs/heads/master
i:
  210685: 81fa634
  210683: 69505cc
  210679: a74335d
  210671: d97dfb7
  210655: 7e2ec68
  210623: e2c663d
  210559: a6b45e6
  210431: 1062752
v: v3

Author: geofft

[refs]

@@ -2,7 +2,7 @@
 refs/heads/master: 3e561f05c00cd180ec02db4ccab2840a4aba93d2
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: ba0e1cd8147d452c356aacb29fb87568ca26f111
-refs/heads/try: 8d50216e9dfb055d28abf9da35f91542c2e9fe90
+refs/heads/try: f59f41e04c044f322285f80d17916bd207d8ed04
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/dist-snap: ba4081a5a8573875fed17545846f6f6902c8ba8d
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596

branches/try/src/doc/trpl/match.md

@@ -61,3 +61,40 @@ let number = match x {
 ```
 
 Sometimes it’s a nice way of converting something from one type to another.
+
+# Matching on enums
+
+Another important use of the `match` keyword is to process the possible
+variants of an enum:
+
+```rust
+enum Message {
+    Quit,
+    ChangeColor(i32, i32, i32),
+    Move { x: i32, y: i32 },
+    Write(String),
+}
+
+fn quit() { /* ... */ }
+fn change_color(r: i32, g: i32, b: i32) { /* ... */ }
+fn move_cursor(x: i32, y: i32) { /* ... */ }
+
+fn process_message(msg: Message) {
+    match msg {
+        Message::Quit => quit(),
+        Message::ChangeColor(r, g, b) => change_color(r, g, b),
+        Message::Move { x: x, y: y } => move_cursor(x, y),
+        Message::Write(s) => println!("{}", s),
+    };
+}
+```
+
+Again, the Rust compiler checks exhaustiveness, so it demands that you
+have a match arm for every variant of the enum. If you leave one off, it
+will give you a compile-time error unless you use `_`.
+
+Unlike the previous uses of `match`, you can’t use the normal `if`
+statement to do this. You can use the [`if let`][if-let] statement,
+which can be seen as an abbreviated form of `match`.
+
+[if-let][if-let.html]