Catch to effect updates (#707)

* Update catchToEffect docs.

* clean up

Author: mbrandonw

Sources/ComposableArchitecture/Effect.swift

@@ -328,7 +328,7 @@ extension Publisher {
   ///
   /// ```swift
   /// case .buttonTapped:
-  ///   return fetchUser(id: 1)
+  ///   return environment.fetchUser(id: 1)
   ///     .catchToEffect()
   ///     .map(ProfileAction.userResponse)
   /// ```
@@ -340,31 +340,27 @@ extension Publisher {
       .eraseToEffect()
   }
 
-  /// Turns any publisher into an ``Effect`` that cannot fail by wrapping its output and failure into
-  /// result and then applying passed in function to it.
+  /// Turns any publisher into an ``Effect`` that cannot fail by wrapping its output and failure
+  /// into a result and then applying passed in function to it.
   ///
-  /// This is a convenience operator for writing `catchToEffect()` followed by a `map()` .
+  /// This is a convenience operator for writing ``Effect/catchToEffect()`` followed by a
+  /// ``Effect/map(_:)-28ghh``.
   ///
   /// ```swift
   /// case .buttonTapped:
-  ///   return fetchUser(id: 1)
-  ///     .catchToEffect {
-  ///       switch $0 {
-  ///       case let .success(response):
-  ///         return ProfileAction.updatedUser(response)
-  ///       case let .failure(error):
-  ///         return ProfileAction.failedUserUpdate(error)
-  ///       }
-  ///     }
+  ///   return environment.fetchUser(id: 1)
+  ///     .catchToEffect(ProfileAction.userResponse)
   /// ```
   ///
   /// - Parameters:
-  ///   - f: A mapping function that converts `Result<Output,Failure>` to another type.
+  ///   - transform: A mapping function that converts `Result<Output,Failure>` to another type.
   /// - Returns: An effect that wraps `self`.
-  public func catchToEffect<T>(_ f: @escaping (Result<Output, Failure>) -> T) -> Effect<T, Never> {
+  public func catchToEffect<T>(
+    _ transform: @escaping (Result<Output,Failure>) -> T
+  ) -> Effect<T, Never> {
     self
-      .catchToEffect()
-      .map(f)
+      .map { transform(.success($0)) }
+      .catch { Just(transform(.failure($0))) }
       .eraseToEffect()
   }
 

Tests/ComposableArchitectureTests/EffectTests.swift

@@ -7,7 +7,7 @@ final class EffectTests: XCTestCase {
   var cancellables: Set<AnyCancellable> = []
   let scheduler = DispatchQueue.test
 
-  func testEraseToEffectWithError() {
+  func testCatchToEffect() {
     struct Error: Swift.Error, Equatable {}
 
     Future<Int, Error> { $0(.success(42)) }