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assign_parameters

This example illustrates the use of assignable variables and parametric objects as alternative implementation to dynamic object predicates for storing (backtrackable) object state. For more information on assignable variables please consult the URL:

http://www.kprolog.com/en/logical_assignment/

The objects in this example make use of the library category assignvars. This category contains an adaptation of the pure logical subset implementation of assignable variables by Nobukuni Kino, which can be found on the URL above.

Print Logtalk, Prolog backend, and kernel versions (if running as a notebook):

%versions

Start by loading the example:

logtalk_load(assign_parameters(loader)).

Rectangle example (don't use message broadcasting syntax in order to workaround a XSB parser bug):

rectangle(2, 3, S)::init, rectangle(2, 3, S)::position(X0, Y0), rectangle(2, 3, S)::move(3, 7), rectangle(2, 3, S)::position(X1, Y1), rectangle(2, 3, S)::move(2, 5), rectangle(2, 3, S)::position(X2, Y2).

<!-- X0 = 0, Y0 = 0, X1 = 3, Y1 = 7, X2 = 2, Y2 = 5. -->

Finite state machine example:

{fsm(T, I, F)}::recognise([0,1,1,2,1,2,0]).

<!-- red-0-red red-1-green green-1-yellow yellow-2-red red-1-green green-2-red red-0-red

T = [red-0-red, red-1-green, red-2-red, yellow-0-red, yellow-1-green, yellow-2-red, green-0-yellow, ... -... -yellow, ... -...], I = red, F = [red]. -->

Finite state machine example:

{fsm(T, I, F)}::recognise([0,1,1,2,1,2,1,0]).

<!-- red-0-red red-1-green green-1-yellow yellow-2-red red-1-green green-2-red red-1-green green-0-yellow backtracking... backtracking... backtracking... backtracking... backtracking... backtracking... backtracking... backtracking...

false. -->