Lambda Expressions and Closures: Master Functional Programming Concepts

Question 1

In Python, which syntax represents a valid lambda expression?

Accepted Answer

(lambda x: x + 1)

Answer

def lambda x: x + 1

Answer

lambda(x: x + 1)

Answer

x => x + 1

Question 2

In JavaScript, what is the primary purpose of a closure?

Accepted Answer

Encapsulate data and behavior within a single unit

Answer

Prevent variable leakage into the global scope

Answer

Enhance code performance by reducing function calls

Answer

Abstract away implementation details from the caller

Question 3

Which of the following is NOT an advantage of using lambda expressions?

Accepted Answer

Increased code complexity

Answer

Improved code readability

Answer

Enhanced code reusability

Answer

Increased code modularity

Question 4

Differentiate between a lambda expression and an anonymous function.

Accepted Answer

Lambda expressions are more concise than anonymous functions.

Answer

Anonymous functions are more efficient than lambda expressions.

Answer

Lambda expressions can replace anonymous functions in all contexts.

Answer

Anonymous functions can replace lambda expressions in all contexts.

Question 5

What is the result of executing the following Python code? `lambda x: x * 2(5)`

Accepted Answer

10

Answer

5

Answer

Error

Answer

None

Question 6

The primary purpose of a closure is to:

Accepted Answer

Create a new scope for variables used within a lambda expression

Answer

Prevent variables from being garbage collected

Answer

Cache data to enhance performance

Answer

Encapsulate data and methods within an object

Question 7

The correct syntax for a lambda expression is:

Accepted Answer

(parameter) -> expression

Answer

-> expression

Answer

parameter -> expression

Answer

expression -> parameter

Question 8

A key difference between a closure and an inner function is that:

Accepted Answer

Closures can access external variables, while inner functions cannot

Answer

Inner functions can access external variables, while closures cannot

Answer

Closures are anonymous, while inner functions are named

Answer

Inner functions are anonymous, while closures are named

Question 9

Which of the following is NOT an advantage of using lambda expressions?

Accepted Answer

Increased code duplication

Answer

Improved code readability

Answer

Enhanced modularity

Answer

Reduced code complexity

Question 10

In the code segment: int sum = [1, 2, 3].stream().reduce(0, Integer::sum); What value is stored in 'sum'?

Accepted Answer

6

Answer

1

Answer

3

Answer

9

Question 11

When should a final variable be used in a lambda expression?

Accepted Answer

To prevent the variable from being modified

Answer

To make the variable accessible from outside the closure

Answer

To enhance performance by caching the variable value

Answer

To ensure the variable is initialized before use

Question 12

Consider the code: int count = 0; Runnable runnable = () -> count++; What is the potential issue with this code?

Accepted Answer

The variable 'count' is not thread-safe

Answer

The lambda expression may lead to a memory leak

Answer

The code will result in unexpected behavior

Answer

There is no issue with this code

Question 13

Lambda expressions are a syntactic sugar for which Java construct?

Accepted Answer

Anonymous Inner Classes

Answer

Regular Expressions

Answer

Interfaces

Answer

Enumerations

Question 14

In which scenario is it more suitable to use a lambda expression instead of a closure?

Accepted Answer

When a simple, anonymous function that does not access the enclosing scope is required

Answer

When accessing variables from the enclosing scope is necessary

Answer

When creating a new instance of a class is necessary

Question 15

What is the defining characteristic of a closure?

Accepted Answer

A function that can access variables from its enclosing scope, even after the function has returned

Answer

An anonymous function that can be assigned to a variable and passed as a value

Answer

A mechanism to enforce data encapsulation and information hiding

Answer

A way to create private variables within a function

Question 16

Which of the following is NOT a characteristic of closures?

Accepted Answer

Closures are always anonymous functions, meaning they cannot have a named identifier.

Answer

Closures can access variables from their enclosing scope, even if those variables are modified later.

Answer

Closures can be passed around as values, allowing for greater code flexibility.

Answer

Closures can modify the variables in their enclosing scope, potentially leading to unexpected behavior.

Question 17

Which of the following is a characteristic of lambda expressions?

Accepted Answer

Anonymous function

Answer

Fixed return type

Answer

Cannot capture variables from the surrounding scope

Answer

Cannot be assigned to a variable

Question 18

What is the primary function of a closure?

Accepted Answer

To allow access to variables outside the scope of the lambda expression

Answer

To pass data between different functions

Answer

To create a new scope for the lambda expression

Answer

To improve code performance

Question 19

How does the performance of lambda expressions and closures compare to traditional function calls?

Accepted Answer

Performance depends on factors like code complexity and usage.

Answer

Lambda expressions are always faster.

Answer

Traditional function calls are always faster.

Answer

There's no noticeable performance difference.

Question 20

In lambda expressions, what is the term for the ability to access variables defined in the enclosing scope?

Accepted Answer

Variable capture

Answer

Variable isolation

Answer

Variable passing

Answer

Variable restriction

Question 21

What is the main purpose of using closures in lambda expressions?

Accepted Answer

To access variables from the enclosing scope

Answer

To improve code performance

Answer

To prevent variables from being accessed outside the lambda expression

Answer

To define new variables within the lambda expression

Question 22

Which of the following is a valid syntax for a lambda expression with no parameters?

Accepted Answer

() -> 10

Answer

(int) -> 10

Answer

()-> 10

Answer

(int) 10

Question 23

What is the key difference between lambda expressions and anonymous inner classes?

Accepted Answer

Lambda expressions are more concise and do not require defining a class

Answer

Lambda expressions are more performant than anonymous inner classes

Answer

Anonymous inner classes can access private variables of the enclosing class

Question 24

Which of the following interfaces is used to represent a function with two arguments?

Accepted Answer

java.util.function.BiFunction

Answer

java.util.function.Function

Answer

java.util.function.Predicate

Answer

java.util.stream.Stream

Question 25

A functional interface in Java is defined as:

Accepted Answer

An interface with exactly one abstract method

Answer

An interface that implements the Comparable interface

Answer

An interface with several abstract methods

Answer

An interface that extends the Runnable interface

Question 26

The primary benefits of using lambda expressions and closures in programming include:

Accepted Answer

Increased code readability, enhanced modularity, improved reusability, and simplified event handling

Answer

Reduced code complexity and enhanced performance

Answer

Fewer errors and improved maintainability

Question 27

How do lambda expressions enhance code readability and maintainability?

Accepted Answer

They promote code conciseness and reduce boilerplate code.

Answer

They enhance code encapsulation and information hiding.

Answer

They provide better type safety and error handling.

Answer

They improve code performance by optimizing memory usage.

Question 28

Which option is NOT an advantage of using lambda expressions?

Accepted Answer

Reduced memory usage

Answer

Enhanced code reusability

Answer

Improved code readability

Answer

Increased modularity

Question 29

What is the primary purpose of a closure in lambda expressions?

Accepted Answer

Capturing and preserving variables from the enclosing scope

Answer

Passing data between different functions

Answer

Creating new variables within the lambda

Question 30

Which of the following code snippets correctly defines a lambda expression?

Accepted Answer

() -> { System.out.println("Hello, world!"); }

Answer

-> () { echo "Hello, world!"; }

Answer

function() { console.log("Hello, world!"); }

Answer

=> () -> { console.log("Hello, world!"); }

Question 31

How do lambda expressions differ from anonymous functions?

Accepted Answer

Lambda expressions do not require naming, while anonymous functions do.

Answer

Lambda expressions are more efficient than anonymous functions.

Answer

Anonymous functions can capture variables, but lambda expressions cannot.

Question 32

Which of the following is an example of a higher-order function that utilizes closures?

Accepted Answer

A function that returns a function to increment a counter

Answer

A function that takes two numbers and returns their sum

Answer

A function that sorts a list of strings

Question 33

What is the main benefit of using lambda expressions in event listeners?

Accepted Answer

Improved code readability and maintainability

Answer

Faster execution speed

Answer

Easier debugging

Answer

Increased security

Question 34

Enhanced: What is the fundamental difference between eager and lazy evaluation in lambda expressions?

Accepted Answer

Revised: Eager evaluation processes the expression upfront, while lazy evaluation defers evaluation until the result is required.

Answer

Eager evaluation is inherently faster, whereas lazy evaluation is noticeably slower.

Question 35

Enhanced: Which potential drawback should be considered when excessively employing lambda expressions?

Accepted Answer

Revised: Increased code complexity and heightened debugging challenges

Answer

Significant performance degradation

Answer

Substantial memory consumption

Question 36

Enhanced: What is the primary purpose of utilizing a lambda expression within a forEach loop?

Accepted Answer

Revised: Iterating over a collection, executing a specified action for each element

Answer

Sorting a collection

Answer

Generating a new collection

Question 37

Enhanced: Which code snippet accurately defines a lambda expression in Java syntax?

Accepted Answer

Revised: () -> {}

Answer

-> : {}

Answer

function() {}

Question 38

Enhanced: What is the fundamental purpose of closures in programming?

Accepted Answer

Revised: Preserving the execution environment (including variable bindings) of the enclosing function

Answer

Enhancing code readability

Answer

Creating anonymous functions

Question 39

Enhanced: Which code snippet accurately captures a local variable using a closure in Java?

Accepted Answer

{ int x = 5; return () -> x; }

Answer

{ int x = 5; return () -> {int x = 10;}; }

Answer

int x = 5; return () -> x; }

Answer

{ int x = 5; return () -> x * 2; }

Question 40

Enhanced: What primary advantage do lambda expressions offer over anonymous inner classes?

Accepted Answer

Revised: Increased code brevity and reduced complexity

Answer

Independence from the enclosing class

Answer

Greater flexibility in method signatures

Answer

Superior performance

Question 41

Enhanced: Which code snippet represents a valid example of a higher-order function that accepts a lambda expression as an argument?

Accepted Answer

Revised: public void forEach(Consumer<Integer> consumer) {}

Answer

public int sum(int a, int b) {}

Answer

public lambda lambda() {}

Answer

public void print(String s) {}

Question 42

Enhanced: What key benefit do lambda expressions provide when defining event listeners?

Accepted Answer

Revised: Improved code readability and reduced boilerplate code

Answer

Enhanced event handling flexibility

Answer

Increased performance

Question 43

Enhanced: Which code snippet correctly utilizes a lambda expression to sort a list of integers in ascending order?

Accepted Answer

Revised: list.sort((a, b) -> a - b);

Answer

list.sort((b, a) -> a - b);

Answer

list.sort(a -> a - b);

Answer

list.sort((a, b) -> b - a);

Question 44

What is the purpose of a closure in programming?

Accepted Answer

To access variables from an enclosing scope outside the lifetime of the function

Answer

To enhance code reusability

Answer

To improve code readability

Question 45

Which of the following best describes a lambda expression?

Accepted Answer

An anonymous function that can be passed as an argument or assigned to a variable.

Answer

A data structure used to store a collection of key-value pairs.

Answer

A named function that can be used to create new objects.

Question 46

What is the primary advantage of using lambda expressions over traditional named functions?

Accepted Answer

Increased code conciseness and readability.

Answer

Improved performance due to reduced function call overhead.

Answer

Simplified debugging by providing clear stack traces.

Answer

Enhanced security by preventing unauthorized access to function code.

Question 47

What is a closure in the context of lambda expressions?

Accepted Answer

A function that captures and retains access to variables from its surrounding scope even after the outer function has finished executing.

Answer

A mechanism for creating new objects based on an existing object's template.

Question 48

Consider the following code snippet: `const add = (x, y) => x + y;`. What is the type of `add`?

Accepted Answer

A function.

Answer

A data structure.

Answer

A class.

Answer

A variable.

Question 49

Which of the following is NOT a valid use case for lambda expressions?

Accepted Answer

Implementing complex algorithms with intricate logic.

Answer

Creating event handlers for user interactions.

Answer

Passing a custom sorting function to a sorting algorithm.

Question 50

What is the primary purpose of capturing variables from the surrounding scope within a closure?

Accepted Answer

To provide the lambda expression with access to relevant data from the enclosing context.

Answer

To increase the scope of the variables, making them accessible globally.

Answer

To prevent data modification by external code.

Question 51

How does a closure differ from a simple function?

Accepted Answer

A closure maintains access to variables from its enclosing scope, while a simple function does not.

Answer

A closure can only be called within the same scope where it was defined, while a simple function can be called anywhere.

Answer

A closure is defined using a different syntax than a simple function.

Question 52

Given the following code: `const outer = () => { let x = 10; const inner = () => { console.log(x); }; return inner; }; const myClosure = outer(); myClosure();` What will be printed to the console?

Accepted Answer

10

Answer

undefined

Answer

Error: x is not defined

Answer

1

Question 53

Which of the following is NOT a benefit of using closures in programming?

Accepted Answer

Improved performance by eliminating the need for function calls.

Answer

Data encapsulation and information hiding.

Answer

Creation of private variables and methods.

Question 54

What is the primary reason for using lambda expressions and closures in functional programming?

Accepted Answer

To promote a more declarative and concise programming style.

Answer

To enhance security by preventing data corruption.

Answer

To improve the efficiency of code execution.