feat: Adds documentation and removes some unused code.

Sources/ComposableSubscriber/Internal/ReceiveOperation.swift

@@ -0,0 +1,78 @@
+import ComposableArchitecture
+
+// A container that holds onto the required data for embedding a task result into
+// an action and optionally transforming the output.
+@usableFromInline
+struct ReceiveOperation<Action, Value, Result> {
+
+  @usableFromInline
+  let embed: @Sendable (TaskResult<Result>) -> Action
+
+  @usableFromInline
+  let operation: @Sendable () async throws -> Value
+
+  @usableFromInline
+  let transform: @Sendable (Value) -> Result
+
+  @usableFromInline
+  func callAsFunction(send: Send<Action>) async {
+    await send(embed(
+      TaskResult { try await operation() }
+        .map(transform)
+    ))
+  }
+
+  @usableFromInline
+  static func `case`(
+    _ casePath: AnyCasePath<Action, TaskResult<Result>>,
+    _ operation: @escaping @Sendable () async throws -> Value,
+    _ transform: @escaping @Sendable (Value) -> Result
+  ) -> Self {
+    .init(embed: { casePath.embed($0) }, operation: operation, transform: transform)
+  }
+
+  @usableFromInline
+  static func `case`(
+    _ casePath: AnyCasePath<Action, TaskResult<Result>>,
+    operation: @escaping @Sendable () async throws -> Value,
+    embedIn embedInCase: AnyCasePath<Result, Value>
+  ) -> Self {
+    .case(casePath, operation) {
+      embedInCase.embed($0)
+    }
+  }
+}
+
+extension ReceiveOperation where Value == Result {
+
+  @usableFromInline
+  init(
+    embed: @escaping @Sendable (TaskResult<Result>) -> Action,
+    operation: @escaping @Sendable () async throws -> Value
+  ) {
+    self.init(embed: embed, operation: operation, transform: { $0 })
+  }
+
+  @usableFromInline
+  static func `case`(
+    _ casePath: AnyCasePath<Action, TaskResult<Result>>,
+    _ operation: @escaping @Sendable () async throws -> Value
+  ) -> Self {
+    .init(embed: { casePath.embed($0) }, operation: operation)
+  }
+}
+
+extension ReceiveOperation where Action: ReceiveAction, Result == Action.ReceiveAction {
+
+  @usableFromInline
+  static func `case`(
+    _ embedInCase: AnyCasePath<Action.ReceiveAction, Value>,
+    _ operation: @escaping @Sendable () async throws -> Value
+  ) -> Self {
+    .case(
+      AnyCasePath(unsafe: Action.receive),
+      operation: operation,
+      embedIn: embedInCase
+    )
+  }
+}