Development systems provide a range of built-in predicates for control of the debugging facilities. The most basic predicates are as follows:
trace/0below), but information prior to this will be unavailable. See mpg-ref-debug.
debug/0, except no debugging information is being collected, and so is almost as fast as running with the debugger switched off. See mpg-ref-zip.
trace/0can also be achieved by typing t after a ^C interruption of a program.
At this point you have a number of options. See Debug Commands. In
particular, you can just type <RET> to creep (or single-step)
into your program. If you continue to creep through your
program you will see every entry and exit to/from every
invocation box, including compiled code, except for code
belonging to hidden modules (see ref-mod). You will
notice that the debugger stops at all ports. However, if this is
not what you want, the next predicate gives full
control over the ports at which you are prompted.
leash/1does not apply to spypoints, the leashing mode of these can be set using the advanced debugger features; see Advanced Debugging. Block and Unblock ports cannot be leashed. Mode can be a subset of the following, specified as a list of the following:
The following shorthands are also allowed:
The initial value of Leashing Mode is
[call,exit,redo,fail,exception] (full leashing).