Initial commit

lib/core/use_case.dart

@@ -0,0 +1,18 @@
+/// A use case represents a single unit of work in the application.
+abstract interface class UseCase<Input, Output> {
+  Output call(Input input);
+}
+
+/// A use case that returns a Future of [Output].
+abstract interface class FutureUseCase<Input, Output>
+    implements UseCase<Input, Future<Output>> {
+  @override
+  Future<Output> call(Input input);
+}
+
+/// A use case that returns a Stream of [Output].
+abstract interface class StreamUseCase<Input, Output>
+    implements UseCase<Input, Stream<Output>> {
+  @override
+  Stream<Output> call(Input input);
+}