[FIXME: These flags, together with their corresponding handlers, are not user level options. Probably this entire section should be moved to the documentation about the low-level programmer debugging interface.]
Here is the list of evaluator trap options generated by typing
(traps 'full) in Guile. You can also see the default values.
exit-frame no Trap when exiting eval or apply.
apply-frame no Trap when entering apply.
enter-frame no Trap when eval enters new frame.
traps yes Enable evaluator traps.
Called when a procedure is being applied.
Called if:
- evaluator traps are enabled [traps interface], and
- either
apply-frameis enabled [traps interface], or- trace mode is on [debug-options interface], and the procedure being called has the trace property enabled.
cont is a “debug object”, which means that it can be passed to
make-stackto discover the stack at the point of the trap. The apply frame handler's code can capture a restartable continuation if it wants to by usingcall-with-current-continuationin the usual way.tailp is true if this is a tail call
Called when a value is returned from a procedure.
Called if:
- evaluator traps are enabled [traps interface], and
- either
exit-frameis enabled [traps interface], or- trace mode is on [debug-options interface], and the procedure being called has the trace property enabled.
cont is a “debug object”, which means that it can be passed to
make-stackto discover the stack at the point of the trap. The exit frame handler's code can capture a restartable continuation if it wants to by usingcall-with-current-continuationin the usual way.retval is the return value.