/* 

  Mtak benchmark in Picat.

  From 
  http://www.jekejeke.ch/idatab/doclet/prod/en/docs/05_run/15_stdy/06_bench/09_programs/09_mtak/01_mtak.p.html

  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.



/**
 * Prolog code for the tak function benchmark.
 *
 * McCarthys tak function.
 * Modification of the tarai function from Takeuchi.
 *
 * Copyright 2010-2012, XLOG Technologies GmbH, Switzerland
 * Jekejeke Prolog 0.8.3 (a fast and small prolog interpreter)
 */

fun(X,Y,Z,A), X =< Y =>
    Z = A.

fun(X,Y,Z,A) =>
    X1 = X - 1,
    fun(X1,Y,Z,A1),
    Y1 = Y - 1,
    fun(Y1,Z,X,A2),
    Z1 = Z - 1,
    fun(Z1,X,Y,A3),
    fun(A1,A2,A3,A).

mtak =>
    fun(18, 12, 6, M),  
    writeln(M).

mtak2 =>
    fun(18, 12, 6, _M).


go => mtak.

go2 => mtak2.