CS 3520 Homework 4 - Due September 25

Place all of the requested functions in a single file, hw4.scm, and hand it in with submit on the CS filesystem.

Exercise 4.1, Let*

Starting with the implementation of the EoPL 3.5 language in hw4.scm, extend the interpreter with a let* form that acts like Scheme's let*. For example, the program

let* x = 10
     y = x
 in y

should evaluate to 10, and the program

let* f = proc(x) +(x, x)
     g = proc(y) +((f y), (f y))
 in (g 10)

should evaluate to 40.

You will have to modify the grammar to add the new let* form.

Hint: consider writing a helper function

eval-rand-sequence : list-of-sym list-of-expr env -> env

to implement let*.

Last update: Tuesday, September 18th, 2001

mflatt@cs.utah.edu