Add implicit block to do macro

lib/Minilisp.pm

@@ -920,7 +920,7 @@ sub macro_do {
 
   my $body = macro_progn($ts);
 
-  return sub {
+  return create_block("nil", sub {
     my $octx = shift;
     my $ictx = ctx_create($octx);
 
@@ -946,7 +946,7 @@ sub macro_do {
       }
 
     return $result_form->($ictx);
-  }
+  });
 }
 $macros{do} = \&macro_do;
 

t/do.t

@@ -11,3 +11,10 @@
                  (comment lst)
                  lst)
                (list 1 2 3)))
+
+(expect "do - has implicit block nil"
+        (equal 'ok
+               (block nil
+                      (do () (t)
+                          (return 'fail))
+                      'ok)))