🐛 Fixed a data race issue using @MainActor

Author: SwiftyJunnos

Sources/Dripper/Drip.swift

@@ -7,16 +7,20 @@
 
 import Foundation
 
-public struct Drip<State: Observable, Action>: Dripper {
+public struct Drip<State: ObservableState, Action>: Dripper {
+
+    // MARK: Nested Types
+
+    public typealias Dripping = @MainActor (_ state: State, _ action: Action) -> Effect<Action>?
 
     // MARK: Properties
 
-    @usableFromInline let drip: (State, Action) -> Effect<Action>?
+    @usableFromInline let drip: Dripping
 
     // MARK: Lifecycle
 
     @inlinable
-    public init(_ drip: @escaping (_ state: State, _ action: Action) -> Effect<Action>) {
+    public init(_ drip: @escaping Dripping) {
         self.init(internal: drip)
     }
 
@@ -25,7 +29,7 @@ public struct Drip<State: Observable, Action>: Dripper {
     }
 
     @usableFromInline
-    init(internal drip: @escaping (_ state: State, _ action: Action) -> Effect<Action>?) {
+    init(internal drip: @escaping Dripping) {
         self.drip = drip
     }
 

Sources/Dripper/Dripper.swift

@@ -11,8 +11,9 @@ public typealias DripperOf<D: Dripper> = Dripper<D.State, D.Action>
 
 // MARK: - Dripper
 
-public protocol Dripper<State, Action> {
-    associatedtype State: Observable
+@MainActor
+public protocol Dripper<State, Action>: Sendable {
+    associatedtype State: ObservableState
     associatedtype Action
     associatedtype Body
 

Sources/Dripper/DripperBuilder.swift

@@ -8,7 +8,7 @@
 import Foundation
 
 @resultBuilder
-public enum DripperBuilder<State: Observable, Action> {
+public enum DripperBuilder<State: ObservableState, Action> {
     @inlinable
     public static func buildBlock<D: Dripper<State, Action>>(_ dripper: D) -> D {
         dripper
@@ -20,9 +20,20 @@ public enum DripperBuilder<State: Observable, Action> {
     }
 
     @inlinable
+    @MainActor
     public static func buildExpression(
         _ expression: any Dripper<State, Action>
     ) -> Drip<State, Action> {
         Drip(expression)
     }
+
+    @inlinable
+    public static func buildFinalResult<D: Dripper<State, Action>>(_ dripper: D) -> D {
+        dripper
+    }
+
+    @inlinable
+    public static func buildOptional<D: Dripper<State, Action>>(_ wrapped: D?) -> D? {
+        wrapped
+    }
 }

Sources/Dripper/Effect.swift

@@ -33,6 +33,7 @@ public struct Pour<Action>: Sendable {
     }
 
     public func callAsFunction(_ action: Action) {
+        guard !Task.isCancelled else { return }
         pour(action)
     }
 }

Sources/Dripper/Station.swift

@@ -10,18 +10,25 @@ import SwiftUI
 
 public typealias StationOf<D: Dripper> = Station<D.State, D.Action>
 
+public typealias ObservableState = Observable & Sendable
+
 // MARK: - Station
 
 @dynamicMemberLookup
 @MainActor
-public final class Station<State: Observable, Action> {
+public final class Station<State: ObservableState, Action> {
 
     // MARK: Properties
 
-    var state: State
-
+    private var state: State
     private let dripper: any Dripper<State, Action>
 
+    // MARK: Computed Properties
+
+    public var currentState: State {
+        state
+    }
+
     // MARK: Lifecycle
 
     public convenience init(