Kotlin Concepts

Question 1

Kotlin functions are first-class, which means?

Answer 1

they can be stored in variables and data structures, and can be passed as arguments to and returned from other higher-order functions.

You can perform any operations on functions that are possible for other non-function values.

Question 2

Kotlin, as a statically typed programming language means?

Answer 2

variable types are explicitly declared and thus are determined at compile time

Question 3

What is a Higher-order function?

Answer 3

a function that takes functions as parameters, or returns a function.

Question 4

All function types have a parenthesized list of parameter types and a return type: (A, B) -> C
What does this denote?

Answer 4

denotes a type that represents functions that take two arguments of types A and B and return a value of type C. The list of parameter types may be empty, as in () -> A. The Unit return type cannot be omitted.

Question 5

Function types can optionally have an additional receiver type, which is specified before the dot in the notation: the type A.(B) -> C
What does this represent?

Answer 5

represents functions that can be called on a receiver object A with a parameter B and return a value C.

Function literals with receiver are often used along with these

Question 6

Suspending functions belong to a special kind of function type that…?

Answer 6

have a suspend modifier in their notation, such as suspend () -> Unit or suspend A.(B) -> C.

Question 7

To specify that a function type is nullable use… ?

Answer 7

parentheses as follows: ((Int, Int) -> Int)?

Question 8

You can also give a function type an alternative name by…?

Answer 8

using a type alias:

typealias ClickHandler = (Button, ClickEvent) -> Unit

Question 9

function literals are?

Answer 9

functions that are not declared but are passed immediately as an expression.

Question 10

Name two types of function literals?

Answer 10

Lambda expressions & anonymous functions