Coding for university students

Why the differences matter less than they seem

A function, a test, a data structure and a recursive definition mean the same thing in Haskell, Python, C or Java. Students who understand the idea in one language pick up the syntax of the next within weeks.

Our lessons teach the idea first, then show it in the language the unit uses.

Students from other faculties

Engineering, science and business students often take one programming unit with little school computing behind them. They are usually the fastest to improve with a weekly hour, because every concept is new rather than half-remembered.

We start from their own discipline's examples wherever we can.

Renaming fools the diff, not the fingerprints

The renamed copy matched only 20.0% of lines, barely above the hand-built independent solution at 15.4%. On fingerprints it scored 100.0%, because the structure under the names never changed.

Disguise only goes so far

Reordering functions and adding comments brought fingerprints down to 72.7%, still far above the independent solutions at 16.0% and 7.8%. The effort of disguising code is larger than the effort of writing it.

Honest work overlaps a little

Two people solving the same small task share some structure by necessity: the hand-built solution shares 16.0% of fingerprints with ours. That is why a similarity score starts a conversation with a person rather than ending one.

When the simple baseline wins

For a word-for-word copy, the plain diff and the fingerprints agree at 100.0%. If verbatim copying were the only worry, a diff would be enough and far simpler.

The character diff is the weakest of the three: it gave the unrelated program 21.0%, more than the library-counter solution, simply because short programs share common letters and symbols.

What this is, and what it is not

This is a teaching experiment with seven programs we wrote ourselves, not a description of any university's software, which we have not seen. Real similarity tools also strip boilerplate shared by a whole class.

The point for students is simple: write your own solution, and the question never arises.