Dr. Dobb's Sourcebook March/April 1997
(a)
select(t1,prod,'prod='P2'')
join(t1,comp,join(t2,t1,cont,'prod','prodc'),'comp','compc')
print(project(t2,t1,'[total:10=0:total+?cost]{comp:10=comp}{cost:10=?cost}'))
(b)
project(r,prod,'{t:5='s'@'project(t,cont, '[s:5=0:s+(prodc=prod)]')'}{p:5=prod}')
print(r)