Immutability interview questions

12 real Immutability questions from the Functional Programming bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.

1. What is Persistent data structure?

Senior
  1. A.deferring duplication of shared data until a modification is requested, then copying only what is changed
  2. B.the rationale that not changing values in place removes a major source of hidden coupling and hard-to-trace bugs
  3. C.an efficiency technique where an updated immutable collection reuses unchanged parts of the original instead of copying everything
  4. D.a collection that preserves all previous versions of itself whenever it is updated
Reveal the answer + AI explanation — free account

3. Which statement is correct?

Senior
  1. A.Persistent data structure — an efficiency technique where an updated immutable collection reuses unchanged parts of the original instead of copying everything
  2. B.Persistent data structure — deferring duplication of shared data until a modification is requested, then copying only what is changed
  3. C.Persistent data structure — a collection that preserves all previous versions of itself whenever it is updated
  4. D.Persistent data structure — the rationale that not changing values in place removes a major source of hidden coupling and hard-to-trace bugs
Reveal the answer + AI explanation — free account

4. What is Structural sharing?

Senior
  1. A.the rationale that not changing values in place removes a major source of hidden coupling and hard-to-trace bugs
  2. B.deferring duplication of shared data until a modification is requested, then copying only what is changed
  3. C.an efficiency technique where an updated immutable collection reuses unchanged parts of the original instead of copying everything
  4. D.a collection that preserves all previous versions of itself whenever it is updated
Reveal the answer + AI explanation — free account

5. Which term means: "an efficiency technique where an updated immutable collection reuses unchanged parts of the original instead of copying everything"?

Senior
  1. A.Why avoid mutation
  2. B.Structural sharing
  3. C.Persistent data structure
  4. D.Copy-on-write
Reveal the answer + AI explanation — free account

6. Which statement is correct?

Senior
  1. A.Structural sharing — deferring duplication of shared data until a modification is requested, then copying only what is changed
  2. B.Structural sharing — an efficiency technique where an updated immutable collection reuses unchanged parts of the original instead of copying everything
  3. C.Structural sharing — the rationale that not changing values in place removes a major source of hidden coupling and hard-to-trace bugs
  4. D.Structural sharing — a collection that preserves all previous versions of itself whenever it is updated
Reveal the answer + AI explanation — free account

7. What is Copy-on-write?

Mid
  1. A.a collection that preserves all previous versions of itself whenever it is updated
  2. B.deferring duplication of shared data until a modification is requested, then copying only what is changed
  3. C.an efficiency technique where an updated immutable collection reuses unchanged parts of the original instead of copying everything
  4. D.the rationale that not changing values in place removes a major source of hidden coupling and hard-to-trace bugs
Reveal the answer + AI explanation — free account

8. Which term means: "deferring duplication of shared data until a modification is requested, then copying only what is changed"?

Mid
  1. A.Copy-on-write
  2. B.Why avoid mutation
  3. C.Persistent data structure
  4. D.Structural sharing
Reveal the answer + AI explanation — free account

9. Which statement is correct?

Mid
  1. A.Copy-on-write — the rationale that not changing values in place removes a major source of hidden coupling and hard-to-trace bugs
  2. B.Copy-on-write — a collection that preserves all previous versions of itself whenever it is updated
  3. C.Copy-on-write — an efficiency technique where an updated immutable collection reuses unchanged parts of the original instead of copying everything
  4. D.Copy-on-write — deferring duplication of shared data until a modification is requested, then copying only what is changed
Reveal the answer + AI explanation — free account

10. What is Why avoid mutation?

Junior
  1. A.deferring duplication of shared data until a modification is requested, then copying only what is changed
  2. B.a collection that preserves all previous versions of itself whenever it is updated
  3. C.an efficiency technique where an updated immutable collection reuses unchanged parts of the original instead of copying everything
  4. D.the rationale that not changing values in place removes a major source of hidden coupling and hard-to-trace bugs
Reveal the answer + AI explanation — free account

11. Which term means: "the rationale that not changing values in place removes a major source of hidden coupling and hard-to-trace bugs"?

Junior
  1. A.Why avoid mutation
  2. B.Copy-on-write
  3. C.Structural sharing
  4. D.Persistent data structure
Reveal the answer + AI explanation — free account

12. Which statement is correct?

Junior
  1. A.Why avoid mutation — the rationale that not changing values in place removes a major source of hidden coupling and hard-to-trace bugs
  2. B.Why avoid mutation — an efficiency technique where an updated immutable collection reuses unchanged parts of the original instead of copying everything
  3. C.Why avoid mutation — a collection that preserves all previous versions of itself whenever it is updated
  4. D.Why avoid mutation — deferring duplication of shared data until a modification is requested, then copying only what is changed
Reveal the answer + AI explanation — free account

Free to start

Answers, AI explanations, and a scored voice mock interview

Sign up free to check your answers with explanations, ask the AI tutor anything on any question, and take one full AI mock interview — scored like a real panel.

Practice Immutability free