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1. Programming Concepts: Closures and Encapsulation (12 points)
Multiple choice. For each question, mark answers. There may be zero or more than
one.
a. What value is computed for ans by the following OCaml program?
type ’a ref = { mutable contents : ’a }
let x = {contents = 4}
let f : int -> int =
let x = {contents = 2} in
fun (y:int) -> y + x.contents
;; x.contents <- 1
let ans = f x.contents
Q 2 Q 3 Q 4 Q 5
b. After running the following OCaml program, the closure named f will contain value bindings
for which identifiers?
let a : int = 50
let f : int -> int =
let b = 60 in
fun (c:int) -> a + b + c
Q a Q b Q c Q f
c. Consider the (simplified) Pixel class given by the Java code below:
class Pixel {
public int[] rgb = {0, 0, 0};
public Pixel(int r, int g, int b) {
rgb[0] = r; rgb[1] = g; rgb[2] = b;
}
public int[] getComponents() {
return rgb;
}
}
To properly encapsulate the state of Pixel objects, the programmer should:
CIS 120 MIDTERM 1 ALGORITHMS & THEIR LIMITATIONS COMPREHENSIVE EXAM 2026 Complete And Study material 13pages LEARNEXAMS
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