declare
fun {NewQueue}
   Given GivePort={NewPort Given}
   Taken TakePort={NewPort Taken}
   proc {Match Xs Ys}
      case Xs # Ys
      of (X|Xr) # (Y|Yr) then
         X=Y {Match Xr Yr}
      [] nil # nil then skip
      end
   end
in
   thread {Match Given Taken} end
   queue(put:proc {$ X} {Send GivePort X} end
         get:proc {$ X} {Send TakePort X} end)
end