reorganize module

_archive/rhai_engine/rhaibook/ref/dynamic.md

@@ -0,0 +1,47 @@
+Dynamic Values
+==============
+
+A dynamic value can be _any_ type.
+
+```rust
+let x = 42;         // value is an integer
+
+x = 123.456;        // value is now a floating-point number
+
+x = "hello";        // value is now a string
+
+x = x.len > 0;      // value is now a boolean
+
+x = [x];            // value is now an array
+
+x = #{x: x};        // value is now an object map
+```
+
+
+Use `type_of()` to Get Value Type
+---------------------------------
+
+Because [`type_of()`](type-of.md) a dynamic value returns the type of the actual value,
+it is usually used to perform type-specific actions based on the actual value's type.
+
+```js
+let mystery = get_some_dynamic_value();
+
+switch type_of(mystery) {
+    "()" => print("Hey, I got the unit () here!"),
+    "i64" => print("Hey, I got an integer here!"),
+    "f64" => print("Hey, I got a float here!"),
+    "decimal" => print("Hey, I got a decimal here!"),
+    "range" => print("Hey, I got an exclusive range here!"),
+    "range=" => print("Hey, I got an inclusive range here!"),
+    "string" => print("Hey, I got a string here!"),
+    "bool" => print("Hey, I got a boolean here!"),
+    "array" => print("Hey, I got an array here!"),
+    "blob" => print("Hey, I got a BLOB here!"),
+    "map" => print("Hey, I got an object map here!"),
+    "Fn" => print("Hey, I got a function pointer here!"),
+    "timestamp" => print("Hey, I got a time-stamp here!"),
+    "TestStruct" => print("Hey, I got the TestStruct custom type here!"),
+    _ => print(`I don't know what this is: ${type_of(mystery)}`)
+}
+```