Rewrite paragraph in 'match' to be more concise and readable. Start

correcting use of ':' in sentences.
The colon `:` should be used only when the sentence preceeding it is a
complete sentence. If this is not the case, then a `;` should be used;
this denotes that the following fragment is a part of the previous
fragment.

Author: Luke Jones

src/doc/book/documentation.md

@@ -9,7 +9,7 @@ document your project.
 The Rust distribution includes a tool, `rustdoc`, that generates documentation.
 `rustdoc` is also used by Cargo through `cargo doc`.
 
-Documentation can be generated in two ways: from source code, and from
+Documentation can be generated in two ways; from source code, and from
 standalone Markdown files.
 
 ## Documenting source code
@@ -73,7 +73,7 @@ hello.rs:4 }
 ```
 
 This [unfortunate error](https://github.com/rust-lang/rust/issues/22547) is
-correct: documentation comments apply to the thing after them, and there's
+correct; documentation comments apply to the thing after them, and there's
 nothing after that last comment.
 
 [rc-new]: https://doc.rust-lang.org/nightly/std/rc/struct.Rc.html#method.new
@@ -385,7 +385,7 @@ error handling. Lets say you want the following,
 
 ```rust,ignore
 /// use std::io;
-/// let mut input = String::new(); 
+/// let mut input = String::new();
 /// try!(io::stdin().read_line(&mut input));
 ```
 
@@ -398,7 +398,7 @@ don't return anything so this will give a mismatched types error.
 /// ```
 /// use std::io;
 /// # fn foo() -> io::Result<()> {
-/// let mut input = String::new(); 
+/// let mut input = String::new();
 /// try!(io::stdin().read_line(&mut input));
 /// # Ok(())
 /// # }

src/doc/book/match.md

@@ -23,26 +23,18 @@ match x {
 `match` takes an expression and then branches based on its value. Each ‘arm’ of
 the branch is of the form `val => expression`. When the value matches, that arm’s
 expression will be evaluated. It’s called `match` because of the term ‘pattern
-matching’, which `match` is an implementation of. There’s an [entire section on
+matching’, which `match` is an implementation of. There’s a [separate section on
 patterns][patterns] that covers all the patterns that are possible here.
 
 [patterns]: patterns.html
 
-So what’s the big advantage? Well, there are a few. First of all, `match`
-enforces ‘exhaustiveness checking’. Do you see that last arm, the one with the
-underscore (`_`)? If we remove that arm, Rust will give us an error:
+One of the many advantages of `match` is it enforces ‘exhaustiveness checking’. For example if we remove the last arm with the underscore `_`, the compiler will give us an error:
 
 ```text
 error: non-exhaustive patterns: `_` not covered
 ```
 
-In other words, Rust is trying to tell us we forgot a value. Because `x` is an
-integer, Rust knows that it can have a number of different values – for
-example, `6`. Without the `_`, however, there is no arm that could match, and
-so Rust refuses to compile the code. `_` acts like a ‘catch-all arm’. If none
-of the other arms match, the arm with `_` will, and since we have this
-catch-all arm, we now have an arm for every possible value of `x`, and so our
-program will compile successfully.
+Rust is telling us that we forgot a value. The compiler infers from `x` that it can have any positive 32bit value; for example 1 to 2,147,483,647. The `_` acts as a 'catch-all', and will catch all possible values that *aren't* specified in an arm of `match`. As you can see with the previous example, we provide `match` arms for integers 1-5, if `x` is 6 or any other value, then it is caught by `_`.
 
 `match` is also an expression, which means we can use it on the right-hand
 side of a `let` binding or directly where an expression is used:
@@ -60,7 +52,7 @@ let number = match x {
 };
 ```
 
-Sometimes it’s a nice way of converting something from one type to another.
+Sometimes it’s a nice way of converting something from one type to another; in this example the integers are converted to `String`.
 
 # Matching on enums
 
@@ -91,7 +83,7 @@ fn process_message(msg: Message) {
 
 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 `_`.
+will give you a compile-time error unless you use `_` or provide all possible arms.
 
 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,

src/doc/book/patterns.md

@@ -7,7 +7,7 @@ on a whirlwind tour of all of the things patterns can do!
 [bindings]: variable-bindings.html
 [match]: match.html
 
-A quick refresher: you can match against literals directly, and `_` acts as an
+A quick refresher; you can match against literals directly, and `_` acts as an
 ‘any’ case:
 
 ```rust