Not uncommonly. The first instance I can remember was during an automata & formal languages class: I dreamt of cars pulling out of parking spaces and going back

Not uncommonly. The first instance I can remember was during an automata & formal languages class: I dreamt of cars pulling out of parking spaces and going back in, and on waking realized that it had to do with the pumping lemma for regular languages. Last night there was a coding dream, but I don't remember the details.