Additional speaker notes for variant payloads (#200)

* Additional speaker notes for variant payloads

* Update variant-payloads.md

* Update variant-payloads.md

src/enums/variant-payloads.md

@@ -9,10 +9,14 @@ You can define richer enums where the variants carry data. You can then use the
 
 <details>
 
-* In the above example, accessing the `char` in `KeyPress`, or `x` and `y` in `Click` only works within a `match` or an `if let` statement.
-* `match` and `if let` inspect a hidden discriminant field in the `enum`.
+* The values in the enum variants can only be accessed after being pattern matched. The pattern binds references to the fields in the "match arm" after the `=>`.
+  * The expressions is matched against the patterns from top to bottom. There is no fall-through like in C or C++.
+  * The match expression has a value. The value is the last expression in the match arm which was executed.
+  * Starting from the top we look for what pattern matches the value then run the code following the arrow. Once we find a match, we stop. 
+* Demonstrate what happens when the search is inexhaustive. Note the advantage the Rust compiler provides by confirming when all cases are handled. 
+* `match` inspects a hidden discriminant field in the `enum`.
 * It is possible to retrieve the discriminant by calling `std::mem::discriminant()`
   * This is useful, for example, if implementing `PartialEq` for structs where comparing field values doesn't affect equality.
-* `WebEvent::Click { ... }` is not exactly the same as `WebEvent::Click(Click)` with a top level `struct Click { ... }`. The inlined version cannot implement traits, for example.
-
+* `WebEvent::Click { ... }` is not exactly the same as `WebEvent::Click(Click)` with a top level `struct Click { ... }`. The inlined version cannot implement traits, for example.  
+  
 </details>