And it turns out that marking many of the JSON functions stable was an oversight and was corrected in git a few days ago: http://git.postgresql.org/gitweb/?p=p

And it turns out that marking many of the JSON functions stable was an oversight and was corrected in git a few days ago: http://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=d788121aba3425b5d52fe20cc9facb6aca1294ce http://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;... So now it is indeed possible!