declare
proc {For A B S P}
   proc {LoopUp C}
      if C=<B then {P C} {LoopUp C+S} end
   end
   proc {LoopDown C}
      if C>=B then {P C} {LoopDown C+S} end
   end
in
   if S>0 then {LoopUp A} end
   if S<0 then {LoopDown A} end
end