Problem
A Problem has a ProblemType, indicating its basic nature and severity. This helps a ProblemHandler decide how best to respond to the Problem, such as deciding whether to continue parsing to discover subsequent problems or to give up building the modules.
Author
Mark van Gulik
Inheritors
Functions
Handle the specified problem, continuing or aborting as indicated by the appropriate problem type handler.
A Problem occurred while executing Avail code. Typically this means an unhandled exception, or invoking a bootstrap primitive before the relevant exception handling mechanisms are in place.
An external Problem occurred. This indicates a failure in something outside the control of the virtual machine, for example a disk read failure.
One of the ProblemType-specific handler methods was invoked, but (1) it was not specifically overridden in the subclass, and (2) this method was not specifically overridden in the subclass. Always fail in this circumstance.
The corresponding Problem is not actually an unexpected condition, but it may still be useful to report the information to the user. It's unclear whether this will actually be used for anything other than debugging the compiler.
An internal Problem occurred in the virtual machine. This should not happen, and is not the fault of the Avail code, but rather Yours Truly, the Avail virtual machine authors.
A Problem occurred while tracing a module's dependencies.
The corresponding Problem indicates a situation that is less than ideal. A ProblemHandler may choose to present this warning, and then continue compilation.