xo-interpreter2 stack: lambda expr -> closure runs in VSM utest

xo-interpreter2/src/interpreter2/DClosure.cpp

@@ -10,6 +10,7 @@
 
 namespace xo {
     using xo::mm::AGCObject;
+    using xo::print::APrintable;
 
     namespace scm {
 
@@ -69,6 +70,24 @@ namespace xo {
             return shallow_size();
         }
 
+        // ----- printable facet -----
+
+        bool
+        DClosure::pretty(const ppindentinfo & ppii) const
+        {
+            obj<APrintable,DLambdaExpr> lambda_pr(const_cast<DLambdaExpr *>(lambda_));
+            obj<APrintable,DLocalEnv> env_pr(const_cast<DLocalEnv *>(env_));
+
+            bool lambda_present = lambda_pr;
+            bool env_present = env_pr;
+
+            return ppii.pps()->pretty_struct
+                (ppii,
+                 "DClosure",
+                 refrtag("lambda", lambda_pr, lambda_present),
+                 refrtag("env", env_pr, env_present));
+        }
+
     } /*namespace scm*/
 } /*namespace xo*/