8.4.2 Tracing

Tracing is enabled with the chr_trace/0 predicate and disabled with the chr_notrace/0 predicate.

When enabled the tracer will step through the call, exit, fail, wake and apply ports, accepting debug commands, and simply write out the other ports.

The following debug commands are currently supported:

        CHR debug options:

                <cr>    creep           c       creep
                s       skip
                g       ancestors
                n       nodebug
                b       break
                a       abort
                f       fail
                ?       help            h       help

Their meaning is:

creep

Step to the next port.

skip

Skip to exit port of this call or wake port.

ancestors

Print list of ancestor call and wake ports.

nodebug

Disable the tracer.

break

Enter a recursive Prolog top level. See break/0.

abort

Exit to the top level. See abort/0.

fail

Insert failure in execution.

help

Print the above available debug options.