Yes, an assertion would have been fine. You're right. Thanks, Matthias, and I apologize again. I look forward to reading your revised Part IV. I learned a lot from reading current versions of HtDP. And if I may say, I like using ormap in this way:
You can search a Sudoku puzzle for a Visible Pair (2 cells in some unit having the same 2 possibilities) that's useful by (define (findVP Sudoku) (ormap proc listofPairs)) using the list of all cell-pairs in all the units, where `proc' is defined using `and' to return either false or the Visible Pair plus the list of cells with possibilities eliminated by the Visible Pair. _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
