declare
fun {NewQueue}
   X C={NewCell q(0 X X)}
   proc {Insert X}
   N S E1 in
      q(N S X|E1)=@C
      C:=q(N+1 S E1)
   end
   fun {Delete}
   N S1 E X in
      q(N X|S1 E)=@C
      C:=q(N-1 S1 E)
      X
   end
in
   queue(insert:Insert delete:Delete)
end