1. A method of compiling a declarative event-driven model specification, comprising: providing a declarative event-driven model specification to a compiler, the event-driven model specification comprising a declarative description of operation of an event-driven system; and generating, by the compiler from the description in the provided declarative event-driven model specification, an executable file comprising a sequence of execution steps for execution on a computer to carry out run-time processing of events in the event-driven system according to the description in the event-driven model specification while also generating, for each of a plurality of elements in the description in the provided declarative event-driven model specification, a cross-reference that relates the element to each of at least one of the execution steps generated therefrom by the compiler, wherein the generated cross-references are usable, in combination with the declarative event-driven model specification and the generated executable file, by a debugger, during debugging of execution of the declarative event-driven model specification, for visibly linking any selected one of the execution steps to the element from which it was generated.