A computer-implemented method for debugging an executable control flow graph that specifies control flow among a plurality of functional modules, with the control flow being represented as transitions among the plurality of functional modules, the computer-implemented method including: specifying a position in the executable control flow graph at which execution of the executable control flow graph is to be interrupted; wherein the specified position represents a transition to a given functional module, a transition to a state in which contents of the given functional module are executed or a transition from the given functional module; starting execution of the executable control flow graph in an execution environment; and at a point of execution representing the specified position, interrupting execution of the executable control flow graph; and providing data representing one or more attributes of the execution environment in which the given functional module is being executed.