~/talk

The Surprising Effectiveness of Immutable Data Structures

Talkat PyCon US 2026 · 2026-05-13..05-19· [developer-experience]
links:none on file
slides:none on file

Claim is that immutability concretely reduces bugs and unlocks performance not just aesthetics The talk shows a real bug where mutable Fibonacci state hides a logic error and converting to frozen dataclasses forces creation of new instances which exposes and fixes the bug Examples include a Fibonacci generator that now returns distinct objects and a memoized path using functools.cache that gives large speedups The pipeline and map pattern composes well with concurrent.futures to gain parallelism and easier testing and reproducibility

AI-written summary · about

  1. 0:00Functional programming intro
  2. 4:13Core value of immutability
  3. 7:20Pure functions and sandwich
  4. 10:06Reassignment vs mutability
  5. 11:30Debugging mutable state bugs
  6. 15:43Fixing bugs with frozen data
  7. 19:54Referential transparency and caching
  8. 23:00Composition and higher-order functions
  9. 29:37Why functional patterns reduce bugs
  10. 33:08Immutable data in parallel computing
  11. 35:57Built-in immutable data structures
  12. 38:47Conclusion and key takeaways
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