clay: flop syntax error trace
^- pile
=/ [=hair res=(unit [=pile =nail])] ((pile-rule pax) [1 1] tex)
?^ res pile.u.res
- %- mean
+ %- mean %- flop
=/ lyn p.hair
=/ col q.hair
:~ leaf+"syntax error at [{<lyn>} {<col>}] in {<pax>}"
