Procedures That Return Multiple Values

• Exercises
  • Exercise 0: Preparation
  • Exercise 1: Testing mixed-number-parts
  • Exercise 2: Computing with Multiple Results
  • Exercise 3: Tallying By Parity
  • Exercise 4: Separating Association Lists
• Notes

Exercises

Exercise 0: Preparation

Scan through the reading on procedures that retun multiple values.

Exercise 1: Testing mixed-number-parts

What are the results of applying mixed-number-parts to each of the following values? Explain each result.

• 17/5
• 4/7
• 40/2
• -2/5
• -10/3
• 1.3
• -0.5

Exercise 2: Computing with Multiple Results

What do you expect to happen when you add 2 to the result of (mixed-number parts 7/5)? Try it and see.

Exercise 3: Tallying By Parity

Define and test a procedure tallies-by-parity that takes any list of integers as its argument and returns two values, the number of even integers in the list and the number of odd integers in the list.

Hint: Use tail recursion.

You may not use partition in your solution.

a. Solve the problem without using call-with-values.

b. Solve the problem with call-with-values

Exercise 4: Separating Association Lists

Define and test a recursive procedure that takes an association list als as argument and returns two results: a list of the keys of als, and a list of the values of als.

Notes