It seems to me that this goal used to work (at least last year) but now I have an error message:

use_rendering(svgtree),Tree = node(node(nil,b,node(nil,ccc,nil)),a,node(nil,d,nil)).

No permission to call sandboxed `retractall('swish renderer'(_1762,_1764))'
Reachable from:

Is there something I can do to display Tree as an svg tree?

use_rendering/1 is a SWISH directive. That works fine. See SWISH -- SWI-Prolog for SHaring

Thank you Jan.
But the code I posted did work last year. I have just checked it using a one year old docker image of swish

I guess so :slight_smile: It shouldn’t though. use_rendering/1 is correctly flagged as a possible breach of the sandbox. The directive is expanded into something that is safe.