Ch8, Ex13

Only method Trans inside TMClass is changed to following:

meth Trans(P ?R TS)
   Halt={NewName}
   T=trans(stamp:TS save:{NewDictionary} body:P
           state:{NewCell running} result:R)
   proc {ExcT C X Y} S1 S2 in
      {proc {$}
          {@tm getlock(T C S1)}
       end}
      if S1==halt then raise Halt end end
      {@tm savestate(T C S2)} {Wait S2}
      {Exchange C.state X Y}
   end
   proc {AccT C ?X} {ExcT C X X} end
   proc {AssT C X} {ExcT C _ X} end
   proc {AboT} {@tm abort(T)} R=abort raise Halt end end
   SubThread %Change: New Addition
in
   %Change here
   thread {NewThread
           proc {$}
              try Res={T.body t(access:AccT assign:AssT
                                exchange:ExcT abort:AboT
                                subthread:SubThread)}
              in {@tm commit(T)} R=commit(Res)
              catch E then
                 if E\=Halt then {@tm abort(T)} R=abort(E) end
              end end SubThread} end
end 

If one needs to start another thread inside the transaction then it can use {T.subthread <0-argument-proc>} to do so.