[feat]: add primary associated types to Workflow protocol

Author: jamieQ

Workflow/Sources/Workflow.swift

@@ -49,37 +49,71 @@
 /// }
 /// ```
 ///
-public protocol Workflow: AnyWorkflowConvertible {
-    /// Defines the state that is managed by this workflow.
-    associatedtype State
+#if swift(>=5.7)
+    public protocol Workflow<Rendering, Output>: AnyWorkflowConvertible {
+        /// Defines the state that is managed by this workflow.
+        associatedtype State
 
-    /// `Output` defines the type that can be emitted as output events.
-    associatedtype Output = Never
+        /// `Output` defines the type that can be emitted as output events.
+        associatedtype Output = Never
 
-    /// `Rendering` is the type that is produced by the `render` method: it
-    /// is commonly a view / screen model.
-    associatedtype Rendering
+        /// `Rendering` is the type that is produced by the `render` method: it
+        /// is commonly a view / screen model.
+        associatedtype Rendering
 
-    /// This method is invoked once when a workflow node comes into existence.
-    ///
-    /// - Returns: The initial state for the workflow.
-    func makeInitialState() -> State
+        /// This method is invoked once when a workflow node comes into existence.
+        ///
+        /// - Returns: The initial state for the workflow.
+        func makeInitialState() -> State
 
-    /// Called when a new workflow is passed down from the parent to an existing workflow node.
-    ///
-    /// - Parameter previousWorkflow: The workflow before the update.
-    /// - Parameter state: The current state.
-    func workflowDidChange(from previousWorkflow: Self, state: inout State)
+        /// Called when a new workflow is passed down from the parent to an existing workflow node.
+        ///
+        /// - Parameter previousWorkflow: The workflow before the update.
+        /// - Parameter state: The current state.
+        func workflowDidChange(from previousWorkflow: Self, state: inout State)
 
-    /// Called by the internal Workflow infrastructure to "render" the current state into `Rendering`.
-    /// A workflow's `Rendering` type is commonly a view or screen model.
-    ///
-    /// - Parameter state: The current state.
-    /// - Parameter context: The workflow context is the composition point for the workflow tree. To use a nested
-    ///                      workflow, instantiate it based on the current state, then call `rendered(in:key:outputMap:)`.
-    ///                      This will return the child's `Rendering` type after creating or updating the nested workflow.
-    func render(state: State, context: RenderContext<Self>) -> Rendering
-}
+        /// Called by the internal Workflow infrastructure to "render" the current state into `Rendering`.
+        /// A workflow's `Rendering` type is commonly a view or screen model.
+        ///
+        /// - Parameter state: The current state.
+        /// - Parameter context: The workflow context is the composition point for the workflow tree. To use a nested
+        ///                      workflow, instantiate it based on the current state, then call `rendered(in:key:outputMap:)`.
+        ///                      This will return the child's `Rendering` type after creating or updating the nested workflow.
+        func render(state: State, context: RenderContext<Self>) -> Rendering
+    }
+#else
+    public protocol Workflow: AnyWorkflowConvertible {
+        /// Defines the state that is managed by this workflow.
+        associatedtype State
+
+        /// `Output` defines the type that can be emitted as output events.
+        associatedtype Output = Never
+
+        /// `Rendering` is the type that is produced by the `render` method: it
+        /// is commonly a view / screen model.
+        associatedtype Rendering
+
+        /// This method is invoked once when a workflow node comes into existence.
+        ///
+        /// - Returns: The initial state for the workflow.
+        func makeInitialState() -> State
+
+        /// Called when a new workflow is passed down from the parent to an existing workflow node.
+        ///
+        /// - Parameter previousWorkflow: The workflow before the update.
+        /// - Parameter state: The current state.
+        func workflowDidChange(from previousWorkflow: Self, state: inout State)
+
+        /// Called by the internal Workflow infrastructure to "render" the current state into `Rendering`.
+        /// A workflow's `Rendering` type is commonly a view or screen model.
+        ///
+        /// - Parameter state: The current state.
+        /// - Parameter context: The workflow context is the composition point for the workflow tree. To use a nested
+        ///                      workflow, instantiate it based on the current state, then call `rendered(in:key:outputMap:)`.
+        ///                      This will return the child's `Rendering` type after creating or updating the nested workflow.
+        func render(state: State, context: RenderContext<Self>) -> Rendering
+    }
+#endif
 
 extension Workflow {
     public func workflowDidChange(from previousWorkflow: Self, state: inout State) {}