declare
fun {NewParser Rules}
   proc {Parse Goal S0 S}
      case Goal
      of nil then S0=S
      [] G|Gs then S1 in
         {Parse G S0 S1}
         {Parse Gs S1 S}
      [] t(X) then S0=X|S
      else if {IsProcedure Goal} then
         {Goal}=true
         S0=S
      else Body Rs in /* Goal is a nonterminal */
         Rs=Rules.{Label Goal}
         {ChooseRule Rs Goal Body}
         {Parse Body S0 S}
      end end
   end
   proc {ChooseRule Rs Goal Body}
      I={Space.choose {Length Rs}}
   in
      rule(Goal Body)={{List.nth Rs I}}
   end
in
   Parse
end