Update CONTRIBUTING.md

CONTRIBUTING.md

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 # Contributing
 
-We accept contributions via Pull Requests on [GitHub](https://github.com/kitetail/zttp).
+Most important:
+
+**This library does not use type-hints, follow PSR-2, or apply most other "best practices."**
+
+This is intentional, and mostly just to make life a little more fun. Life's too short to take everything so seriously.
+
+The library is still high quality and has an awesome test suite; it's just written more like Ruby than like Java :)
+
+## Code Style
+
+This library borrows most structural choices from PSR-2 in terms of tabs vs. spaces, where there should/shouldn't be whitespace, and where to put braces.
+
+It deviates significantly from PSR-1 and PSR-2 in the following ways:
+
+- Instance properties **must not be declared** (unfortunately PHP won't let you omit static properties), instead assign them dynamically in `__construct`
+- Visibility keywords (public, protected, private) **must not be used**
+
+For example:
+
+```php
+// Bad! 😒
+class Foo
+{
+    private $bar;
+    private $baz = 'hello world';
+
+    public function __construct()
+    {
+        $this->bar = new Collection;
+    }
+
+    private function qux()
+    {
+        // ...
+    }
+}
+
+// Fantastic! 😍
+class Foo
+{
+    function __construct()
+    {
+        $this->bar = new Collection;
+        $this->baz = 'hello world';
+    }
+
+    function qux()
+    {
+        // ...
+    }
+}
+```
+
+Additionally, code must also follow these constraints:
+
+- Type-hints **must not be used**
+- Temporary variables **must not be used**
+- Each method **must return immediately**; methods cannot have more than one expression
 
 ## Pull Requests
 
+We accept contributions via Pull Requests on [GitHub](https://github.com/kitetail/zttp).
+
 - **Add tests!** - Your patch won't be accepted if it doesn't have tests.
-- **Document any change in behaviour** - Make sure the `README.md` and any other relevant documentation are kept up-to-date.
 - **One pull request per feature** - If you want to do more than one thing, send multiple pull requests.
 - **Send coherent history** - Make sure each individual commit in your pull request is meaningful. If you had to make multiple intermediate commits while developing, please squash them before submitting.