timer-effect.patch

diff --git a/0084-testable-state-management-ergonomics/PrimeTime/ComposableArchitecture/ComposableArchitecture.swift b/0084-testable-state-management-ergonomics/PrimeTime/ComposableArchitecture/ComposableArchitecture.swift
index db4ab12..ab96c5f 100644
--- a/0084-testable-state-management-ergonomics/PrimeTime/ComposableArchitecture/ComposableArchitecture.swift
+++ b/0084-testable-state-management-ergonomics/PrimeTime/ComposableArchitecture/ComposableArchitecture.swift
@@ -128,3 +128,24 @@ public func logging<Value, Action>(
       }] + effects
   }
 }
+
+
+extension Publisher where Failure == Never {
+  public func cancellable<Id: Hashable>(id: Id) -> Effect<Output> {
+    return Deferred { () -> PassthroughSubject<Output, Failure> in
+      cancellables[id]?.cancel()
+      let subject = PassthroughSubject<Output, Failure>()
+      cancellables[id] = self.subscribe(subject)
+      return subject
+    }
+    .eraseToEffect()
+  }
+
+  public static func cancel<Id: Hashable>(id: Id) -> Effect<Output> {
+    .fireAndForget {
+      cancellables[id]?.cancel()
+    }
+  }
+}
+
+private var cancellables: [AnyHashable: AnyCancellable] = [:]
diff --git a/0084-testable-state-management-ergonomics/PrimeTime/Counter/Counter.swift b/0084-testable-state-management-ergonomics/PrimeTime/Counter/Counter.swift
index fb61f6c..4a0a770 100644
--- a/0084-testable-state-management-ergonomics/PrimeTime/Counter/Counter.swift
+++ b/0084-testable-state-management-ergonomics/PrimeTime/Counter/Counter.swift
@@ -1,6 +1,7 @@
 import ComposableArchitecture
 import PrimeModal
 import SwiftUI
+import Combine
 
 public enum CounterAction: Equatable {
   case decrTapped
@@ -8,6 +9,7 @@ public enum CounterAction: Equatable {
   case nthPrimeButtonTapped
   case nthPrimeResponse(Int?)
   case alertDismissButtonTapped
+  case receivedTimer
 }
 
 public typealias CounterState = (
@@ -18,13 +20,25 @@ public typealias CounterState = (
 
 public func counterReducer(state: inout CounterState, action: CounterAction) -> [Effect<CounterAction>] {
   switch action {
+  case .receivedTimer:
+    print("Timer received!")
+    return []
+
   case .decrTapped:
     state.count -= 1
-    return []
+    return [
+      .cancel(id: "timer")
+    ]
 
   case .incrTapped:
     state.count += 1
-    return []
+    return [
+      Timer.publish(every: 1, on: .main, in: .default)
+        .autoconnect()
+        .map { _ in CounterAction.receivedTimer }
+        .eraseToEffect()
+        .cancellable(id: "timer")
+    ]
 
   case .nthPrimeButtonTapped:
     state.isNthPrimeButtonDisabled = true