Initial Flutter booru app

lib/core/utils/logger.dart

@@ -0,0 +1,13 @@
+import 'package:flutter/foundation.dart';
+
+class AppLogger {
+  const AppLogger();
+
+  void debug(String message, [Object? error, StackTrace? stackTrace]) {
+    if (kDebugMode) {
+      debugPrint('[GelRule] $message');
+      if (error != null) debugPrint('  error: $error');
+      if (stackTrace != null) debugPrint('  stack: $stackTrace');
+    }
+  }
+}

lib/core/utils/result.dart

@@ -0,0 +1,29 @@
+import '../errors/failure.dart';
+
+sealed class Result<T> {
+  const Result();
+
+  bool get isSuccess => this is Success<T>;
+  bool get isError => this is Error<T>;
+
+  R fold<R>({
+    required R Function(T data) onSuccess,
+    required R Function(Failure failure) onError,
+  }) {
+    final current = this;
+    return switch (current) {
+      Success<T>(:final data) => onSuccess(data),
+      Error<T>(:final failure) => onError(failure),
+    };
+  }
+}
+
+class Success<T> extends Result<T> {
+  const Success(this.data);
+  final T data;
+}
+
+class Error<T> extends Result<T> {
+  const Error(this.failure);
+  final Failure failure;
+}