CREATE EXTENSION ltree_plpython3u CASCADE; CREATE FUNCTION test1(val ltree) RETURNS int LANGUAGE plpython3u TRANSFORM FOR TYPE ltree AS $$ plpy.info(repr(val)) return len(val) $$; SELECT test1('aa.bb.cc'::ltree); CREATE FUNCTION test1n(val ltree) RETURNS int LANGUAGE plpython3u TRANSFORM FOR TYPE ltree AS $$ plpy.info(repr(val)) return len(val) $$; SELECT test1n('aa.bb.cc'::ltree); CREATE FUNCTION test2() RETURNS ltree LANGUAGE plpython3u TRANSFORM FOR TYPE ltree AS $$ return ['foo', 'bar', 'baz'] $$; -- plpython to ltree is not yet implemented, so this will fail, -- because it will try to parse the Python list as an ltree input -- string. SELECT test2();