# Functional Data Structures and Algorithms by Tobias Nipkow

2 Hacker News commenters recommended Functional Data Structures and Algorithms by Tobias Nipkow and 2 criticized it, November 2025 to November 2026. It was recommended in 2 of 13 months.

**Verdict:** Recommended for learning functional data structures and algorithms with a proof assistant, but critics say its runtime analysis is informal and not checked.

## What people warn about

- Runtime behaviour not proven (3 comments): "That does not help you much if you want to know how many seconds this will run." ([source](https://news.ycombinator.com/item?id=46071133)) "this book unfortunately only proves correctness directly and not runtime" ([source](https://news.ycombinator.com/item?id=46066177)) "This approach doesn't do that. The translation from the actual executing code to the representation used for runtime analysis is done entirely informally and not checked at all by Isabelle." ([source](https://news.ycombinator.com/item?id=46070828))
- Runtime analysis done informally (2 comments): "This approach doesn't do that. The translation from the actual executing code to the representation used for runtime analysis is done entirely informally and not checked at all by Isabelle." ([source](https://news.ycombinator.com/item?id=46070828)) "the book is treating Isabelle definitions as runnable code" ([source](https://news.ycombinator.com/item?id=46086481))

## Alternatives hackers recommend

- [Structure and Interpretation of Computer Programs by Abelson and Sussman](https://hackerapproved.com/p/structure-and-interpretation-of-computer-programs.md): 55 recommend
- [The Art of Computer Programming by Donald E. Knuth](https://hackerapproved.com/p/art-of-computer-programming.md): 28 recommend
- [Structure and Interpretation of Computer Programs by Abelson and Sussman](https://hackerapproved.com/p/sicp.md): 12 recommend
- [Quantum Computation and Quantum Information by Nielsen and Chuang](https://hackerapproved.com/p/quantum-computation-and-quantum-information.md): 12 recommend
- [Digital Design and Computer Architecture by Harris and Harris](https://hackerapproved.com/p/digital-design-and-computer-architecture.md): 8 recommend

## Where to get it

- [See price on Amazon](https://www.amazon.com/s?k=9798400731563&tag=hackerapprove-20) (affiliate link)
- [Bookshop.org](https://bookshop.org/a/130825/9798400731563) (affiliate link)

## Cite as

Hacker Approved, "Functional Data Structures and Algorithms by Tobias Nipkow", https://hackerapproved.com/p/functional-data-structures-and-algorithms-a-proof-assistant-approach/ (counts from 1,795,640 Hacker News comments, November 2025 to November 2026).