senior-software-developer-questions/functional-programming.md at master · fjod/senior-software-developer-questions · GitHub

Functional programming

Books

FP checklist

What is arity? How to get function arity in JS?
What is first-class citizen? What is it in JS?
What are the consequences of the fact that in JS functions are also first-class citizen?
What is a higher order function?
Control flow
- What?
- How does it affect code complexity?
- What are the features of control flow in programs written in a functional paradigm?
Partial use of functions and currying
- When can partial application of functions be useful?
- When can currying be useful?
- What are their differences?
- What is their influence on the arity of functions?
Function Composition
- What?
- What is it used for?
- What is a pipe?
- How to implement the compose function?
Point-free style
- What?
- What advantages can give?
- What could be the disadvantages?
What are side effects? How are they harmful and how are they useful?
What are pure functions? What are dirty functions? What are the advantages of some over others?
Can a dirty call come from a pure function? If so, what does it mean?
How to limit the effect of "dirty functions" on the system?
What is idempotency? What is the difference between software and mathematical idempotency?
What is link transparency? Is referential transparency of a function call expression a sufficient sign of the purity of this function?
Immutability
- What?
- Are objects contained in variables declared with const immutable?
- What are the advantages of immune data structures?
- What is structural sharing and what problems does it solve?
Recursion
- What?
- What are the advantages and disadvantages of the application?
- What is tail call optimization? Is it supported in JS?
Study the book [Professor Frisby's Mostly Adequate Guide to Functional Programming] (https://github.com/MostlyAdequate/mostly-adequate-guide) by Franklin Frisby (chapters 8-12 included).
- [Translation] (https://github.com/MostlyAdequate/mostly-adequate-guide-ru)
Explore the book [Functional-Light JavaScript] (https://github.com/getify/Functional-Light-JS) by Kyle Simpson (chapters 9-11, plus additions).
How to implement the functionality of objects through closures and vice versa? What are the advantages of each method?
How can I create private values in a function? How can they be made immune?
What are categories? What are morphisms?
What is isomorphism?
What is a functor?
How can I avoid unnecessary passes through the array?
What is lazy computing? What are the advantages and disadvantages of lazy computing?
What is transduction? What problems can be solved with this tool?
What is a pointed functor?
What are monads? What are they used for? What do the monads below do?
- Maybe
- Either
- IO
What is associativity?
What is an applicative functor? What is the scope of its application?
What do the following utilities do?
- identity
- partial / partialRight
- prop
- curry / uncurry
- cond
- flatMap / chain
Immutability and state
- Can the state of the program be immutable?
- What is the problem of storing the state of the program?
- Why does a mutable state make it difficult to comply with the guarantee of invariants throughout the program life cycle?
- Why does mutability impose additional requirements on the order of functions? How can this be avoided?
- Describe the following state models. How can they be graded according to the degree of danger?
  - Invisible to the client mutable state
  - Encapsulated mutable state
  - Invisible programmer mutable state
  - Two-phase life cycle
  - A mutable state shared between several processes
  - Lack of mutable state
  - Unencapsulated mutable state
  - Managed mutable state
  - Monotonous variable state

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