---

yaml
---
r: 36829
b: refs/heads/try2
c: e0072e3
h: refs/heads/master
i:
  36827: ed4813c
v: v3

Author: graydon

[refs]

@@ -5,7 +5,7 @@ refs/heads/snap-stage3: eb8fd119c65c67f3b1b8268cc7341c22d39b7b61
 refs/heads/try: d324a424d8f84b1eb049b12cf34182bda91b0024
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b
-refs/heads/try2: 46766974c73ff17a3b2cd4f2fb2cb06b7845ded4
+refs/heads/try2: e0072e39a788ada2a636ab88a0b97534544c4125
 refs/heads/incoming: d9317a174e434d4c99fc1a37fd7dc0d2f5328d37
 refs/heads/dist-snap: 22efa39382d41b084fde1719df7ae8ce5697d8c9
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596

branches/try2/doc/rust.md

@@ -1503,6 +1503,39 @@ values.
 ("a", 4u, true);
 ~~~~~~~~
 
+### Structure expressions
+
+~~~~~~~~{.ebnf .gram}
+struct_expr : expr_path '{' ident ':' expr
+                      [ ',' ident ':' expr ] *
+                      [ ".." expr ] '}'
+~~~~~~~~
+
+A _structure expression_ consists of the [path](#paths) of a [structure item](#structures),
+followed by a brace-enclosed list of one or more comma-separated name-value pairs,
+providing the field values of a new instance of the structure.
+A field name can be any identifier, and is separated from its value expression by a colon.
+To indicate that a field is mutable, the `mut` keyword is written before its name.
+
+The following are examples of structure expressions:
+
+~~~~
+Point {x: 10f, y: 20f};
+game::User {name: "Joe", age: 35u, mut score: 100_000};
+~~~~
+
+A structure expression forms a new value of the named structure type.
+
+A structure expression can terminate with the syntax `..` followed by an expression to denote a functional update.
+The expression following `..` (the base) must be of the same structure type as the new structure type being formed.
+A new structure will be created, of the same type as the base expression, with the given values for the fields that were explicitly specified,
+and the values in the base record for all other fields.
+
+~~~~
+let base = Point3d {x: 1, y: 2, z: 3};
+Point3d {y: 0, z: 10, .. base};
+~~~~
+
 ### Record expressions
 
 ~~~~~~~~{.ebnf .gram}
@@ -1511,9 +1544,11 @@ rec_expr : '{' ident ':' expr
                [ ".." expr ] '}'
 ~~~~~~~~
 
+> **Note:** In future versions of Rust, record expressions and [record types](#record-types) will be removed.
+
 A [_record_](#record-types) _expression_ is one or more comma-separated
-name-value pairs enclosed by braces. A fieldname can be any identifier
-(including keywords), and is separated from its value expression by a
+name-value pairs enclosed by braces. A fieldname can be any identifier,
+and is separated from its value expression by a
 colon. To indicate that a field is mutable, the `mut` keyword is
 written before its name.