Clarify renderer API, add ChildrenType

Example/Gluon/ViewController.swift

@@ -31,6 +31,8 @@ import Gluon
 //}
 
 struct Counter: LeafComponent {
+  typealias Props = NoProps
+
   static func render(props: NoProps) -> Node {
     let (count, setCount) = hooks.state(0)
 

Gluon/Source/Structs.swift

@@ -7,16 +7,28 @@
 
 import Foundation
 
+extension Never: Equatable {
+  public static func == (lhs: Never, rhs: Never) -> Bool {
+    switch (lhs, rhs) {
+    }
+  }
+}
+
 /// Type-erased version of Component to work around
 /// the lack of generalized existentials in Swift
 public protocol _Component {
 }
 
+/// Conforming to this protocol, but implementing support for these new types
+/// in a renderer would make that renderer skip unknown types of children.
+public protocol ChildrenType {
+}
+
 /// You should never directly conform to this protocol, use `HostComponent`
 /// for host components and `Component` for composite components.
 public protocol BaseComponent: _Component {
   associatedtype Props: Equatable
-  associatedtype Children: Equatable
+  associatedtype Children: ChildrenType & Equatable
 
   var children: Children { get }
   var props: Props { get }
@@ -26,16 +38,16 @@ public protocol Component: _Component {
   associatedtype Props: Equatable
   associatedtype Children: Equatable
 
-  static func render(props: Props, children: Children)
+  static func render(props: Props, children: Children) -> Node
 }
 
-public protocol LeafComponent: Component where Children == NoProps {
-  static func render(props: Props)
+public protocol LeafComponent: Component where Children == Never {
+  static func render(props: Props) -> Node
 }
 
-extension LeafComponent {
-  static func render(props: Props, children: NoProps) {
-    render(props: props)
+public extension LeafComponent {
+  public static func render(props: Props, children: Children) -> Node {
+    return render(props: props)
   }
 }
 
@@ -55,37 +67,43 @@ extension Component {
 }
 
 public struct Node: Equatable {
-  /// Equatable can't be automatically derived for recursive types
+  /// Equatable can't be automatically derived for `type` property?
   public static func == (lhs: Node, rhs: Node) -> Bool {
-    return lhs.type == rhs.type &&
+    return lhs.key == rhs.key &&
+      lhs.type == rhs.type &&
       lhs.children == rhs.children &&
       lhs.props == rhs.props
   }
 
+  let key: String?
   let props: AnyEquatable
-  let children: [Node]
+  let children: AnyEquatable
   let type: _Component.Type
 }
 
-public protocol Child {
-
-}
-
 extension BaseComponent {
-//  init?(props: AnyEquatable, children: [Node]) {
-//    guard let props = props.value as? Props else {
-//      return nil
-//    }
-//
-//    self.init(props: props, children: children)
-//  }
-
-  public static func node(_ props: Props, _ children: Children) -> Node {
-    return Node(props: AnyEquatable(props), children: children, type: self.self)
+  public static func node(key: String? = nil,
+                          _ props: Props,
+                          _ children: Children) -> Node {
+    return Node(key: key,
+                props: AnyEquatable(props),
+                children: AnyEquatable(children),
+                type: self.self)
   }
 }
 
+extension Node: ChildrenType {
+}
+
+extension Array: ChildrenType where Element == Node {
+}
+
+extension String: ChildrenType {
+}
+
 public struct View: BaseComponent {
+  public typealias Children = [Node]
+
   public let props: Props
   public let children: [Node]
 
@@ -94,11 +112,8 @@ public struct View: BaseComponent {
 }
 
 public struct Label: BaseComponent {
-  public let props: Props
-  public let children: [Node]
-
-  public struct Props: Equatable {
-  }
+  public let props: NoProps
+  public let children: String
 }
 
 public struct Button: BaseComponent {

Gluon/Source/UIKitRenderer.swift

@@ -8,17 +8,22 @@
 import Foundation
 
 protocol Renderer {
-
+  func mountTarget(to parent: Any, with component: RendererBaseComponent) -> Any
+  func update(target: Any, with component: RendererBaseComponent)
+  func umount(target: Any, from parent: Any, with component: RendererBaseComponent)
 }
 
 protocol Reconciler {
 
 }
 
-protocol UIKitBaseComponent {
+protocol RendererBaseComponent {
 
 }
 
+protocol UIKitBaseComponent: RendererBaseComponent {
+}
+
 class UIKitRenderer {
 
 }