---

yaml
---
r: 35676
b: refs/heads/master
c: 45e62d0
h: refs/heads/master
v: v3

Author: brson

[refs]

@@ -1,5 +1,5 @@
 ---
-refs/heads/master: d098faa8555d48a9bc1de34542fc6d1dd5a2ab9c
+refs/heads/master: 45e62d0a144f336e2ad849c1bb7767a12f312643
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: eb8fd119c65c67f3b1b8268cc7341c22d39b7b61
 refs/heads/try: d324a424d8f84b1eb049b12cf34182bda91b0024

trunk/doc/tutorial.md

@@ -813,6 +813,15 @@ assert 8  == line(5, 3, 1);
 assert () == oops(5, 3, 1);
 ~~~~
 
+As with `match` expressions and `let` bindings, function arguments support
+pattern destructuring. Like `let`, argument patterns must be irrefutable,
+as in this example that unpacks a tuple and returns it.
+
+~~~
+fn first((value, _): (int, float)) -> int { value }
+~~~
+
+
 # The Rust memory model
 
 At this junction, let's take a detour to explain the concepts involved
@@ -1576,6 +1585,21 @@ fn contains(v: &[int], elt: int) -> bool {
 }
 ~~~~
 
+Notice that, because `each` passes each value by borrowed pointer,
+the iteratee needs to dereference it before using.
+In these situations it can be convenient to lean on Rust's
+argument patterns to bind `x` to the actual value, not the pointer.
+
+~~~~
+# use each = vec::each;
+# fn contains(v: &[int], elt: int) -> bool {
+    for each(v) |&x| {
+        if (x == elt) { return true; }
+    }
+#    false
+# }
+~~~~
+
 `for` syntax only works with stack closures.
 
 > ***Note:*** This is, essentially, a special loop protocol: