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

`filter` returns a new collection containing only the elements for which the given predicate function returns true.

Question 2

What is a closure in Scala?

Accepted Answer

A function that captures variables from its enclosing scope

Answer

A closure is a function that references variables from its surrounding lexical scope, carrying those bindings with it.

Question 3

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

Accepted Answer

fold or reduce

Answer

`fold` and `reduce` are aggregation methods that apply a binary operation across a collection to produce a single accumulated result.

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

Referential transparency means any expression can be substituted with its evaluated result without altering the program's behavior.

Question 5

How are anonymous functions (lambdas) defined in Scala?

Accepted Answer

(x: Int) => x + 1

Answer

Scala anonymous functions use the fat arrow `=>` syntax with optional parameter types: `(x: Int) => x + 1`.

Scala Practice Test