/* 

  Meta interpreter in Picat v3.

  See meta_interpreter_bp_v3_.pi for a version with "import bp".

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

*/


% import bp.

main => go.


go ?=>
  bp.assert($memberx(X,[X|_])),
  bp.assert($(memberx(X,[_|R]) :- memberx(X,R))),
  % This don't work:
  % cl_facts($[
  %     (memberx(X,[X|_])),
  %     (memberx(X,[_|R]) :- memberx(X,R))
  %     ]),
  clause_tree($memberx(X,[a,b,c])),
  writeln(X),
  fail,
  
  nl.

go => true.


go2 =>
  clause_tree($(Y is 3, Y <  5)),
  writeln(Y),
  nl.

go2 => true. 



% From
% https://www.cpp.edu/~jrfisher/www/prolog_tutorial/pt_framer.html
% https://www.cpp.edu/~jrfisher/www/prolog_tutorial/3_3.html
% clause_tree(true) :- !.      /* true leaf */ 
% clause_tree((G,R)) :-
%    !, 
%    clause_tree(G),
%    clause_tree(R).           /* search each branch */ 
% clause_tree(G) :-
%    bp.clause(G,Body), 
%    clause_tree(Body).        /* grow branches */ 

% memberx(X,[X|_]). 
% memberx(X,[_|R]) :- memberx(X,R). 

clause_tree(true) :- !.
clause_tree((G,R)) :-
   !,
   clause_tree(G), 
   clause_tree(R).
clause_tree(G) :-
   bp.predicate_property(G,built_in),
   bp.call(G).              %% let Prolog do it
clause_tree(G) :-
   bp.clause(G,Body),
   clause_tree(Body).