Purpose of the assignment:

• To give you additional practice using recursion

Your assignment:

This one is easy to describe. Write three functions:

• sort, to sort a list of integers into ascending order;
• sortedp, to test whether a list of integers is in ascending order; and
• permutedp, to take two lists of atoms and determine if one list is a permutation (rearrangement) of the atoms in the other list.

You may, of course, write any additional functions you need in order to accomplish the above. These functions form a nice related group, because sortedp and permutedp can be used to test whether the sort function works properly.

Lisp notes:

You will need to be able to compare integers. The functions <, <=, =, /=, >=, and > are all defined in Lisp (along with EQ, which is the same as = when applied to integers). These are functions, not operators, so you would say, for example, (< A B), not (A < B).

XLisp has trouble with file names longer than 8.3 characters; they can be loaded from the menu but not with the load function.

Due date:

Because I was late in getting this assignment posted, the due date will be Monday, February 3, before midnight. The following assignment (in Java) will be due the same week (Thursday, February 6), so there will be some overlap.