Description
In this assignment, you will write a higher-order function for traversing the file system object datatype from the previous assignment. You will then re-implement some of the functions you implemented in the previous assignment using the higher-order function with anonymous functions as arguments. The datatype binding is shown below: datatype FSObject = File of string * int | Link of string * string | Directory of string * (FSObject list) 1. Write a higher-order function traverseFS that takes a file system object and a function for each variant of the FSObject datatype (and a base case for the list variant), and traverses the datatype by applying the right function for each variant. (Hint: Look at your functions from the previous assignment and see what they have in common and where they differ.) 2. Use traverseFS to re-implement totalSize from the previous assignment. Pass anonymous functions to traverseFS. 3. Use traverseFS to re-implement containsLinks from the previous assignment. Pass anonymous functions to traverseFS. 4. Use traverseFS to re-implement getFilesLargerThan from the previous assignment. Pass anonymous functions to traverseFS. 5. Use traverseFS to re-implement countLinksTo from the previous assignment. Pass anonymous functions to traverseFS. 6. This question is unrelated to the previous questions. The following function concatStrings takes a string list and returns a string that is the concatenation of all the strings in the list in order from beginning to end: fun concatStrings xs = case xs of [] => “” | x::xs’ => x ^ concatStrings(xs’) Rewrite this function using tail recursion. Evaluating a correct homework solution should generate the bindings below. However, keep in mind that generating these bindings does not guarantee that your solutions are correct. Make sure to test your functions before submitting. datatype FSObject = Directory of string * FSObject list | File of string * int | Link of string * string val traverseFS = fn : FSObject * (string * int -> ‘a) * (string * string -> ‘a) * ‘a * (‘a * ‘a -> ‘a) -> ‘a val totalSize = fn : FSObject -> int val containsLinks = fn : FSObject -> bool val getFilesLargerThan = fn : FSObject * int -> string list val countLinksTo = fn : FSObject * string -> int val concatStrings = fn : string list -> string Assessment Solutions should be: Correct In good style, including indentation and line breaks Written using features discussed in class Submission Instructions Put all your solutions in one SML file and submit it via Moodle. The file should be named “.sml” where is your AUBnet ID (e.g., abc01.sml). Do not submit any other files or compressed folders.
