Document mapProps receiving a function

Author: nigredo-tori

docs/api/Control.md

@@ -89,18 +89,26 @@ It can also be a function that returns a string model. See [the documentation on
 
 <h2 id="prop-mapProps"></h2>
 ## `mapProps={\{...}}`
-_(Object)_: A mapping of control-specific property keys to prop-getter functions that taken in the original props and return the result prop. See [the documentation on custom controls](../guides/custom-controls.md) for more information.
+_(Object | Function)_: A custom mapping from props provided by `Control` to props received by the component. Can be:
 
-Example:
+- An object, where each value is a function from original props to corresponding value in result props.
+- A function from original props to result props.
+
+Examples:
 ```jsx
 <Control
   mapProps={\{
     customChange: (props) => props.change,
   }}
   model="..."
 />
+<Control
+  mapProps={({change}) => { return {customChange: change}; }}
+  model="..."
+/>
 ```
 
+See [the documentation on custom controls](../guides/custom-controls.md) for more information.
 
 <h2 id="prop-updateOn"></h2>
 ## `updateOn="..."`

docs/guides/custom-controls.md

@@ -137,5 +137,20 @@ Some custom controls won't have prop keys that match up exactly with the standar
 />
 ```
 
-In `mapProps`, the **key** corresponds to the _custom_ control's prop key, and the **value** is a function that takes in the standard `props` applied to `<Control>` and returns the prop value that the custom prop should map to.
+If `mapProps` is an object, the **key** corresponds to the _custom_ control's prop key, and the **value** is a function that takes in the standard `props` applied to `<Control>` and returns the prop value that the custom prop should map to.
 
+
+```jsx
+<Control
+  model="..."
+  component={DatePickerIOS}
+  mapProps={ ({modelValue, onChange}) => {
+    return {
+      date: modelValue,
+      onDateChange: onChange,
+    };
+  }}
+/>
+```
+
+If `mapProps` is a function, it is applied to the standard `props`, and its return value is used as _custom_ control's props.