SWANK-BACKEND::WARN-UNIMPLEMENTED-INTERFACES does correct filling in
SBCL and CMUCL. It does not do any filling on CCL. The filling on Clisp
is suboptimal.
-T.
PS: Instead of the (pprint-newline :fill) [~:_] in
~:<~{~A~^ ~:_~}~:>
perhaps a use of ~:@> would imply it.