The fact that transparent structures also print all of their element - in this case recursively, ad nauseam - is more of a side effect. In that case, I think prop:custom-write properties should be added. I assume any of the print limiting options in my case still walk the entire structure and create a several tens of megabytes long string just to truncate it. <div class="gmail_quote">On Mon, Oct 3, 2011 at 3:52 PM, John Clements <<a href="mailto:clements@brinckerhoff.org">clements@brinckerhoff.org</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"> <div class="im"> On Oct 3, 2011, at 2:13 PM, Doug Williams wrote: > There are ways around it like that. For example, I'm trying to get in the habit of using ~.s in printf's where it might occur. But, I think it would be easy in this case to just fix the real problem. </div>I don't think I would agree that #:transparent is the problem here; #:transparent means "yes, anyone can use the reflective properties to discover how many fields this structure has, what the mutators are, etc." It's not fundamentally about printing. So I think that a separate control on printing is definitely the right way to go, and in particular, the ~.s choice seems like it might just solve the problem completely. No? John </blockquote></div>