<> <> <> DIRECTORY Basics; TopoSort: CEDAR DEFINITIONS = { PartialComparison: TYPE ~ Basics.PartialComparison --{less, equal, greater, incomparable}--; Handle: TYPE ~ REF ANY; <> ListSort: PROC [ alpha, omega: Handle, GetLink: PROC [Handle] RETURNS [Handle], SetLink: PROC [from, to: Handle], Compare: PROC [Handle, Handle] RETURNS [PartialComparison] ]; <> <> <> <> }.