Ah, but you never had to submit assignments of code on paper did you?
Yes. We called them "printouts". :-)
Proofs that a given algorithm worked in a given way would be written by hand on paper; anything that could be run submitted online, with documentation, and paper printouts for the convenience of the teaching assistants who graded most of the assignments.
It was easier for the TAs to run a test suite against the code; verify minimal correctness, and *then* audit the paper copies of the code for style and correctness, and submitting code online just made their lives a bit easier.
Some prof in a data structures class gave an assignment that basically said: "Implement a linked list datastructure in your language of choice"; some guy I knew decided to use Perl (which has list processing pretty much built in). The prof was not pleased; but gave full marks. He was more specific about choice of language the next time. That was back in 1993, so yes, professors know about Perl by now. They may or may not like it, but they know about it.
In reply to Re^5: If I could only own one Perl book, it would be:
by Anonymous Monk