CS 2420-20 Homework 18

Due: Thursday, March 29th, 2012 9:10am

As usual...

Part 1 – Testing Numbers

Start with miniracket5.zip.

Add support for booleans as values and expressions, and also add an iszero form that has a single sub-expression.

Part 2 – Adding Conditionals

Add an if form to the language.

Handin your revised main.c (for new tests), eval.c, print.c, struct.c, struct.h, continue.c, and continue.h.

Here’s an example from recent homework solutions that you might use to test your additions:

  symbol* fib = make_symbol("fib");
  tagged* fib_var = (tagged*)fib;
  tagged *fib_func
    = make_func(n,
                make_branch(make_iszero(n_var),
                            one,
                            make_branch(make_iszero(make_minus(n_var, one)),
                                        one,
                                        make_plus(make_app(fib_var,
                                                           make_minus(n_var,
                                                                      one)),
                                                  make_app(fib_var,
                                                           make_minus(n_var,
                                                                      two))))),
                NULL);
  
  hash_table* fib_d = make_dict();
  
  hash_set(fib_d, fib, fib_func);
  
  check_num_val(eval(make_app(fib_var, make_num(6)), NULL, fib_d),
                13);