/* 

  assert/retract in Picat.

  Using B-Prolog's functionality.
  Note: This usage is not recommended...

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

*/


% import util.
% import cp.


main => go.


go =>
  bp.assert($play(adam,billiards)),
  bp.assert($play(eve,billiards)),
  bp.assert($play(seth,bowling)),
  bp.assert($play(abel,bowling)),
  print_all(),
  nl.

go2 => 
  Data = [
  [adam,billiards],
  [eve,billiards],
  [seth,bowling],
  [abel,bowling]
  ],
  foreach([Who,What] in Data)
     bp.assert($play(Who,What))
  end,
  print_all(),
  nl.

go3 => 
  Data = [
  [adam,billiards],
  [eve,billiards],
  [seth,bowling],
  [abel,bowling]
  ],
  Map = new_map([T=1 : T in Data]),
  foreach([Who,What] in Map.keys())
     bp.assert($play(Who,What))
  end,
  print_all(),
  nl.

print_all =>
  while (bp.retract($play(Who,What)))
    println(Who=What)
  end,
  nl.