CS G111 Machine Problem 5b: Manipulating the Store

Out: October 23, 2007

Due: October 30, 2007

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For this problem, you will extend the language IMPLICIT-REFS, found at /course/csg111/interps/lecture05/implicit-refs.

Do the following exercises:

1. Add multiple-argument procedures and multiple-declaration let-expressions to IMPLICIT-REFS. No rules required for this one. [10 points]
2. Write a rule for let in IMPLICIT-REFS, in the style of the rules on page 21 of the notes. You may use either the "rule" style or the "equation" style. Write this as a comment to the appropriate line of the interpreter. [2 points]

   You should submit a single set of files for questions 1 and 2. In these files, use the test harness drscheme-init.scm, as usual. Your top-level file should be named top-implicit-refs.scm.

3. Implement the statement language given in the notes. The interpreter on page 36 of the notes is available at /course/csg111/interps/mp5/statements.scm. The expressions of your statement language should be the expressions of question 1. [10 points]
4. Add while to the statement language. Write a rule or rules in the style of the rules on page 35 of the notes [3 points], and implement them [5 points]. As in question 2, you may use either the "rule" style or the "equation" style.

   You should submit a single set of files for questions 3 and 4. The top-level file should be named top-statements.scm. This set of files can, but need not, be disjoint from the files for questions 1 and 2.

   Further notes on questions 3 and 4:

   • Use the grammar in the book (Exercise 4.22), not the one in the notes. They differ in the syntax for print, and that the one in the book also has a while statement (which is needed for question 4 of this MP).
   • For questions 3 and 4, we will use a new test setup for this problem that will capture the values that your interpreter prints out.

     To use this setup, the modules in these files should require /course/csg111/interps/mp5/drscheme-mp5-init.scm instead of drscheme-init.scm.

   The implementation of print in statements.scm communicates these values to the test harness by calling logged:printf instead of eopl:printf. You shouldn't need to make any other changes in your interpreter to accomodate this setup.

   • The beginnings of a test suite are in /course/csg111/interps/mp5/tests.scm. You will need to add more tests in this file.
   • The code in statements.scm is untested (sorry!), so it may contain bugs.