Changes

bin/fire.dart

@@ -1,7 +1,8 @@
-import 'dart:io' show FileSystemEntity, exit;
+import 'dart:io' show FileSystemEntity, ProcessResult, exit, stdout;
 
-import 'package:fire/fire.dart';
+import 'package:fire/fire.dart' show FireOutputDelegate, run_fire;
 import 'package:path/path.dart' as path;
+import 'package:stack_trace/stack_trace.dart' show Trace;
 
 Future<void> main(
   final List<String> args,
@@ -19,10 +20,59 @@ Future<void> main(
         args: [
           if (args.isNotEmpty) ...args.sublist(1, args.length),
         ],
+        output: _FireOutputDelegateImpl(
+          output: stdout.writeln,
+        ),
       );
     } else {
       print("'" + file_path + "' not found or isn't a file.");
       exit(2);
     }
   }
 }
+
+class _FireOutputDelegateImpl implements FireOutputDelegate {
+  final void Function(String) output;
+
+  const _FireOutputDelegateImpl({
+    required this.output,
+  });
+
+  @override
+  void output_error(
+    final Object payload,
+    final StackTrace stack_trace,
+  ) {
+    output(payload.toString());
+    output(Trace.format(stack_trace));
+  }
+
+  @override
+  void output_string(
+    final String str,
+  ) {
+    output(str);
+  }
+
+  @override
+  void output_compiler_output(
+    final Iterable<String> values,
+  ) {
+    for (final line in values) {
+      output(line);
+    }
+  }
+
+  @override
+  void redirect_process(
+    final ProcessResult result,
+  ) {
+    // TODO https://stackoverflow.com/questions/33251129/what-is-the-best-way-to-stream-stdout-from-a-process-in-dart
+    if (result.stdout != null) {
+      output(result.stdout.toString().trimRight());
+    }
+    if (result.stderr != null) {
+      output(result.stderr.toString().trimRight());
+    }
+  }
+}