# Recursive Lists

This lesson contains a bunch of classical exercises on recursive lists. It is certainly not the most pleasant lesson to do, but I think that it is the easiest of the PLM lessons dealing with recursion.

As usual, there are several things that could be done in the code of this universe to improve it:

- New exercises could be proposed, such as http://webloria.loria.fr/~quinson/Teaching/TOP/02-td-recursivite-enonce.pdf If you know some others, please report them as an issue.
- It would be interesting to check the asymptotic complexity of the student's code, but that does not sound easy to do. In Python and Java (where we provide a hand-made RecList class), we could count the amount of cons per exercise, but it won't be easy to relate this to the right BatTest. For Scala, it sounds even more difficult as we use the classical :: operators of the language. That will be difficult to override to add a counting mechanism. Another solution would be to ensure that the call stack does not pass a given threshold, but that sounds very difficult too. Any idea is welcome.