This week Adam continued reading Languages and Tools for Hybrid Systems Design by Carloni, Passerone, Pinto, and Sangiovanni-Vincentelli. Among the languages covered by the survey is Shift, which differs from the other languages in the survey in that it supports models whose structure can change during a simulation. Two modern modeling languages which support this type of dynamic models are Acumen and Yampa. Acumen supports this feature in a manner similar to Shift, through the creation, movement and destruction of its natural objects. In Yampa, you can implement a similarly dynamic model by defining it in terms of switching combinators, one of which was discussed in an earlier post. It is still not clear to Adam to what degree languages which support dynamic collections of data need to support dynamic reconfiguration of the model itself. This question is interesting because the latter tends to lead to programs which are difficult to understand.
