Functional Programming

Question 1

What is functional programming?

Answer 1

Functional programming (often abbreviated FP) is the process of building software by composing pure functions, avoiding shared state, mutable data, and side-effects. Functions are first class citizens of such languages.

Question 2

Which is imperative and which is declarative?

Answer 2

FP - Declarative and OOP - Imperative

Question 3

Where does application state reside in FP vs OOP?

Answer 3

Application state flows through pure functions, as opposed to OOP where the state is usually shared and colocated with methods in objects.

Question 4

Examples of some functional languages

Answer 4

LISP, Erlang, Haskell, F#, Clojure,

Question 5

A pure function ____

Answer 5

• Given same input always returns same value

- Has no side effects

Question 6

Function composition is ______

Answer 6

Is process of combining two or more functions to produce new function or produce some output.
f(g(x))

Question 7

Shared state is ______

Answer 7

Any variable, object or memory that is shared scope or is a property of object being passed between scopes.

Question 8

Problems with shared state

Answer 8

• To understand the behavior of function you need to know the history of every shared variable that function uses or affects
• Race condition

Question 9

Examples of side effects

Answer 9

• Changing global variable or shared variable
• Logging to console
• Writing to file
• Writing to network
• Triggering any external process
• Calling other function that has side effects

Question 10

What are higher order functions?

Answer 10

HOF is any function which takes function as argument, returns a function or both. They are at higher abstraction levels.
Eg. Monads, Promise, Async etc