---

yaml
---
r: 210685
b: refs/heads/try
c: 797d8e2
h: refs/heads/master
i:
  210683: 69505cc
v: v3

Author: geofft

[refs]

@@ -2,7 +2,7 @@
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-refs/heads/try: 457aed7ca003d7cbef2cda8360ad9b8b5bb83650
+refs/heads/try: 797d8e28695a9f349a3155958e06c527250bdac9
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
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 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596

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

@@ -177,3 +177,22 @@ println!("length is {} inches", integer_length);
 As you can see here, you can extract the inner integer type through a
 destructuring `let`, just as with regular tuples. In this case, the
 `let Inches(integer_length)` assigns `10` to `integer_length`.
+
+# Unit-like structs
+
+You can define a struct with no members at all:
+
+```rust
+struct Electron;
+```
+
+Such a struct is called ‘unit-like’ because it resembles the empty
+tuple, `()`, sometimes called ‘unit’. Like a tuple struct, it defines a
+new type.
+
+This is rarely useful on its own (although sometimes it can serve as a
+marker type), but in combination with other features, it can become
+useful. For instance, a library may ask you to create a structure that
+implements a certain [trait][trait] to handle events. If you don’t have
+any data you need to store in the structure, you can just create a
+unit-like struct.