EECS 321: Programming Languages —
1 Binding Identifiers
Implement the function binding-ids, which takes a WAE (see lecture code or lecture slides) and produces a list of symbols. The list should contain a symbol for every binding identifier in the given WAE. Each symbol should appear at most once in the list, and the symbols should be ordered according to the symbol<? comparison procedure.
Hint: First, write a function that generates an unordered list of symbols with duplicates, and then write separate functions to re-order the list and then remove duplicates.
filter - takes a predicate and a list, and returns a list that contains only values for which the predicate returned true. This is useful for removing a value from a list.
sort - takes a list and a less-than comparison function (i.e., a function of two arguments where the result is true when the first argument is less than the second) and produces a sorted list.
member - takes a value and a list, and returns false if the value is not in the list, and otherwise returns the portion of the list after (inclusively) the value of interest, which counts as a true value as far as conditionals are concerned.
Of course, you’re also welcome to use other PLAI functions as you see fit.
2 Bound Identifiers
Implement the function bound-ids, which is like binding-ids, but the result list contains a symbol for each bound identifier in the given WAE. The result list of symbols must be sorted and have no duplicates.
3 Free Identifiers
Implement the function free-ids, which is like binding-ids, but the result list contains a symbols for each free identifier in the given WAE. The result list of symbols must be sorted and have no duplicates.
4 Shadowed Identifiers
Implement the function shadowed-ids, which accepts a WAE and returns a list of the binding identifiers that are shadowed by another binding in the given WAE. The result list of symbols must be sorted and have no duplicates.
5 Handin Instructions
Provide definitions for binding-ids, bound-ids, free-ids, and shadowed-ids, as above.
Use the same definition for WAE we used in class.
Have the 8 rules from the Provost’s website (see the homework 1 for more details).
Submit your code using the Handin button in DrRacket.