Homework 3

Due: start of class on Thursday, April 23rd

IMPORTANT NOTES

• This homework is longer than the previous homeworks. Please allocate additional time to do the homework.
• Although you are only turning in hard copies of your code, please make sure your code would work if run on linuxlab.
• This homework must be TYPED.

1. p.300 of PLP, Exercise 6.17(a). Write an iterator function (generator) in PYTHON only. We are giving you some starter code. As you can see in the starter code, the program asks for a number between 2 and 9. If given, for example, 3 -- the program should output all permutations of 123 -- which would be 123 132 213 231 312 321. The way the program is written, it lists each permutation on its own line. Add whatever code you need, but DO implement giveAPermutation as an iterator function and DO NOT change any code after the line of pound signs. A python interpreter can be found on linuxlab. You can refer to class notes and web resources. Print out a copy of your homework3.py (with iterator function implemented) and turn that in as part of the homework submission.
2. p.302 of PLP, Exercise 6.27. Write the function in Scheme only. Do not look for the answer on the internet and then copy it down.
3. p.398 of PLP, Exercise 7.2.
4. Define a function called myif in Scheme. myif takes three parameters: condition, ifTrue, and ifFalse. condition is of boolean type. ifTrue is a function that takes no parameters and should be called when the condition is true. ifFalse is a function that takes no parameters and should be called when the condition is false. You cannot use if or cond. You can, however, use and, or, not, and eq?. Use ONLY the functional features of Scheme. Here is some starter code. Print out a copy of your homework3.scheme (with myif implemented) and turn that in as part of the homework submission.
5. p.553 of PLP, Exercise 10.7 (b).
6. p.554 of PLP, Exercise 10.8 (a) and (b).
7. Write CURRIED versions of the two functions you wrote for 10.8 (a) and (b).