Scala Functional Programming in Scala 2

Question 1

What does the `filter` method do on a Scala collection?

Accepted Answer

Returns only elements satisfying a predicate

Answer

Transforms each element

Answer

Sorts elements

Answer

Removes duplicates

Question 2

What is a closure in Scala?

Accepted Answer

A function that captures variables from its enclosing scope

Answer

A sealed class

Answer

A private object

Answer

An anonymous trait

Question 3

Which Scala method combines all elements of a collection into a single value?

Accepted Answer

fold or reduce

Answer

collect

Answer

flatten

Answer

zip

Question 4

What is referential transparency in functional programming?

Accepted Answer

An expression that can be replaced by its value without changing program behavior

Answer

The ability to reference private fields

Answer

Functions that return references

Answer

Transparent visibility modifiers

Question 5

How are anonymous functions (lambdas) defined in Scala?

Accepted Answer

(x: Int) => x + 1

Answer

function(x) => x + 1

Answer

lambda x: x + 1

Answer

\x -> x + 1

Question 6

What does `collect` do on a Scala collection?

Accepted Answer

Applies a partial function to elements, returning only defined results

Answer

Gathers futures

Answer

Collects all None values

Answer

Groups elements by key