ITEC 380 Program 6

OPTIONAL

Due 11:59:59 p.m. Saturday, December 11, 2010

Submit command: submit itec380-01 intempty.lsp

Write a Common LISP function called intempty that takes two arguments and evaluates to true (ie T) if both arguments are lists and the intersection of the two lists is empty. Otherwise intempty should evaluate to false (ie nil). Note that you must return T for the true value (rather than some other non-nil value).

Note that for either argument, any element of that list can itself be a list. Make sure that your program works correctly in these case. Here are some examples of the program in action:

   (intempty '(1 2 3 4) '(5 6 7)) → T ; Empty
   (intempty '(1 2 3 4) '(5 6  2 7)) → NIL ; 2 common

   (intempty '(1 2 3) ()) → T ; Empty
   (intempty '(1 2 3) 'a) → NIL ; Second argument not a list

   (intempty '(1 (2 3) 4) '(5 (2 3  4))) → T ; Empty
   (intempty '(1 (2 3) 4) '(5 (2 3) 4 )) → NIL ; (2 3) common

You may NOT use setq or other programs with side effects in your program. You may use functions like member, listp, and append, but not any function that effectively does the program for you. In general, if you need a function, you should write it yourself.

Your program should follow good style. In this case this means to use white space to make your program easier to understand (ie easy to match parentheses) and to choose meaningful variable names.

You should also include comments to make the code easier to understand as well as a header comment describing you, the project, etc. In Common Lisp, characters following a semicolon (ie ;) are ignored.

Use /usr/bin/gcl on rucs2 to run Common Lisp. You can use (bye) or control D (perhaps twice) to exit gcl.

You might want to try out the command % in vi to help in writing your lisp code.

Put your program in a file called intempty.lsp and turn it in using this command

                 submit itec380-01 intempty.lsp