CPSC425 Spring 2008
HW 8: Types and Related Topics

1. Read Webber Chapter 8 on Polymorphism. Do exercise 5 at the end of the chapter, all parts. Note that you can check your answers by typing in these functions, but do each exercise by hand first. The last few take some thought; be sure you think hard before you check them.

2. Read Webber Chapter 9, which is primarily about first-class functions in ML. Do exercises 1-15, 27, and 28 at the end of the chapter. Notes:
   • Note the restriction that 1-15 not use any additional named functions or explicit recursion. This is important! These should be one-line solutions as described at the beginning of the exercises, usually using map, foldr, or foldl.
   • We talked about (and even defined) map in class, but not about foldl or foldr. You will need to read about these in the chapter and think carefully about what they do.
   • We similarly did not talk about currying, which you will also read about in the chapter. It's a very powerful concept, but for these exercises will mostly just let you use a slightly nicer syntax to define your functions (no parentheses -- this is the "little secret" on the top of page 140). We'll talk more about currying in class next week.

   Have fun -- this is starting to feel like real functional programming!