/* 

  Shoe problem (planning) in Picat.

  Inspired by
  http://www.idi.ntnu.no/emner/tdt4136/PRO/shoeson.txt
  Attributed to AIMA 2nd edition, Fig 11.6

  This Picat model was created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/


% import util.
import gps_utils.


main => go.


go =>
  Init = $[[start]],
  Final = $[[finish]],
  cl_facts($[final2(Final)]),
  gps_best_plan(Init),

  nl.

final(L) =>
  final2(Final2),
  pre(L,Final2),
  writeln(final=L).


action(From,To,Move,Cost) ?=>
  pre(From,$[[rightshoe_on],[leftshoe_on]]),
  Move = [finish],
  To = From.add([[finish]]),
  Cost = 1.

action(From,To,Move,Cost) ?=>
  pre(From,$[[rightsock_on]]),
  Move = [rightshoe],
  To = From.add($[[rightshoe_on]]),
  Cost = 1.

action(From,To,Move,Cost) ?=>
  % pre(From,[[]]),
  Move = [rightsock],
  To = From.add($[[rightsock_on]]),
  Cost = 1.


action(From,To,Move,Cost) ?=>
  pre(From,$[[leftsock_on]]),
  Move = [leftshoe],
  To = From.add($[[leftshoe_on]]),
  Cost = 1.

action(From,To,Move,Cost) =>
  % pre(From,[[]]),
  Move = [leftsock],
  To = From.add($[[leftsock_on]]),
  Cost = 1.