---

yaml
---
r: 206799
b: refs/heads/beta
c: f59f41e
h: refs/heads/master
i:
  206797: 380d918
  206795: fce9e9b
  206791: ab060f0
  206783: 79ee0df
v: v3

Author: geofft

[refs]

@@ -29,7 +29,7 @@ refs/tags/0.12.0: f0c419429ef30723ceaf6b42f9b5a2aeb5d2e2d1
 refs/heads/automation-fail: 1bf06495443584539b958873e04cc2f864ab10e4
 refs/heads/batch: b7fd822592a4fb577552d93010c4a4e14f314346
 refs/heads/building: 126db549b038c84269a1e4fe46f051b2c15d6970
-refs/heads/beta: 8d50216e9dfb055d28abf9da35f91542c2e9fe90
+refs/heads/beta: f59f41e04c044f322285f80d17916bd207d8ed04
 refs/heads/windistfix: 7608dbad651f02e837ed05eef3d74a6662a6e928
 refs/tags/1.0.0-alpha: e42bd6d93a1d3433c486200587f8f9e12590a4d7
 refs/heads/tmp: 579e31929feff51dcaf8d444648eff8de735f91a

branches/beta/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]