Homework #6

This problem requires Lecture 4 and Lecture 5.

Part A involves writing your first function that is autograded. Make sure it is not commented out. Parts B and C should be in block comments.

Part A
Write the following variable arity functions to handle either 2 or 3 arguments. If you use built-in functions (like +), you may only pass them 2 arguments at a time. Hint: try using if and/or cond.

sum
For example:

> (sum 1 2)
3

> (sum 3 4 5)


Notice:  Uninitialized string offset:  2 in /users/home2/ta/cs330ta/public_html/cs330/inc/codeformat.php on line 115

12

even-parity (true if there are an even number of 1s passed to it, false if there are an odd number of 1s)
For example:
```
> (even-parity 1 0)
#f

> (even-parity 1 0 1)
#t
```

YOU MUST NAME YOUR FUNCTIONS sum AND even-parity

Part B
Translate the following let expression into the equivalent application of a lambda expression to operands:

    (let ((a 3)
          (b (+ 2 3)))
      (+ a b))

Type both this let expression and your equivalent expression using lambda into the interpreter to verify that they work the same way.

Part C
Most languages have features that are just syntactic sugar. Pick a language you like to work with (C++, Java, etc.) and name as many features that you can think of that are syntactic sugar. What other features in the language are they equivalent to?

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Last updated at 9:16 pm on Friday, September 03, 2004.