Prolog "Syntax Error: Operator Expected" Error -


i editing following game , have 2 errors left; both @ bolded , italicized "!." (in forum listed *'s). doesn't happen in other times used , have searched other answers, deleted spaces, etc. , can't seem find answer. please let me know if have advice! :)

the first error after section titled "gate" , after section titled "key"

/*   little adventure game.  there 3   entities: you, treasure, , ogre.  there   6 places: valley, path, cliff, fork, maze,   , mountaintop.  goal treasure   without being killed first. */    /*   first, text descriptions of places in   game. */ description(valley,   'you in pleasant valley, trail ahead.'). description(path,   'you on path, ravines on both sides.'). description(cliff,   'you teetering on edge of cliff.'). description(fork,   'you @ fork in path.'). description(maze(_),   'you in maze of twisty trails, alike.'). description(mountaintop,   'you on mountaintop.'). description(gate,   'you @ gate.'). description(teleport,   'you teleport gate.'). description(key,   'you stuble on rock , under it.'). description(didntdropkey,   'dont forget drop .....').     /*   report prints description of current   location. */ report :-   at(you,x),   description(x,y),   write(y), nl.  assert(at(you,cliff)). report. retract(at(you,cliff)). assert(at(you,valley)). report.    /*   these connect predicates establish map.   meaning of connect(x,dir,y) if   @ x , move in direction dir,   y.  recognized directions   forward, right, , left. */ connect(valley,forward,path). connect(path,right,cliff). connect(path,left,cliff). connect(path,forward,fork). connect(fork,left,maze(0)). connect(fork,right,gate). connect(gate,right,mountaintop). connect(gate,left,didntdropkey). connect(gate,forward,didntdropkey). connect(maze(0),left,maze(1)). connect(maze(0),right,maze(3)). connect(maze(1),left,maze(0)). connect(maze(1),right,maze(2)). connect(key,left,teleport). connect(key,right,maze(0)). connect(maze(3),left,maze(0)). connect(maze(3),right,maze(3)).  /*   move(dir) moves in direction dir,   prints description of new location. */ move(dir) :-   at(you,loc),   connect(loc,dir,next),   retract(at(you,loc)),   assert(at(you,next)),   report,   !. /*   if argument not legal direction,   print error message , don't move. */ move(_) :-   write('that not legal move.\n'),   report.  /*   shorthand moves. */ forward :- move(forward). left :- move(left). right :- move(right).  /*   if , ogre @ same place,   kills you. */ ogre :-   at(ogre,loc),   at(you,loc),   write('an ogre sucks brain out through\n'),   write('your eye sockets, , die.\n'),   retract(at(you,loc)),   assert(at(you,done)),   !. /*   if , ogre not in same place,   nothing happens. */ ogre.  /*   if , treasure @ same place,   win. */  key :-   at(you,key),   write('you have found key'),   retract(at(you,maze(2)),   assert(at(you,key)),   ***!.***  key.     /*  print out you're @ key need  add key used later. */ /* teleport function action taken if key , turn right teleport gate*/  teleport :-     at(you,teleport),     write('you teleported gate'),     retract(at(teleport)),     assert(at(you,gate)),     !. teleport.  didntdropkey :-   at(you,didntdropkey),   write('you didnt drop key , stuck lightning.\n'),   retract(at(you,dintdropkey)),   assert(at(you,done)),   !. didntdropkey.   treasure :-   at(treasure,loc),   at(you,loc),   write('there treasure here.\n'),   write('congratulations, win!\n'),   retract(at(you,loc)),   assert(at(you,done)),   !. /*   if , treasure not in same   place, nothing happens. */ treasure.  /*   if @ cliff, fall off , die. */  gate :- at(you,gate), write('you use key found earlier open gate.\n'), move(at(you, mountaintop), move(at(you, treasure), ***!.***  gate.   cliff :-   at(you,cliff),   write('you fall off , die.\n'),   retract(at(you,cliff)),   assert(at(you,done)),   !. /*   if not @ cliff nothing happens. */ cliff.  /*   main loop.  stop if player won or lost. */ main :-   at(you,done),   write('thanks playing.\n'),   !. /*   main loop.  not done, move user   , make it.  run our special behaviors.   repeat. */ main :-   write('\nnext move -- '),   read(move),   call(move),   ogre,   treasure,   gate,   cliff,   main.  /*   starting point game.    assert initial conditions, print initial   report, start main loop. */ go :-   retractall(at(_,_)), % clean previous runs   assert(at(you,valley)),   assert(at(ogre,maze(3))),   assert(at(treasure,mountaintop)),   write('this adventure game. \n'),   write('legal moves left, right, or forward.\n'),   write('end each move period.\n\n'),   report,   main. 

retract(at(you,maze(2)),                        ^ move(at(you, mountaintop),                          ^ move(at(you, treasure),                       ^

you're missing closing paren in these places. makes prolog think these clauses don't end @ cut.


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