Persistent Data Structures
kimschles edited this page Apr 16, 2019
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1 revision
Lesley Lai, BoulderJS, March 20, 2019
- A persistent data structure
- Example: git is fully preserved on the disk, and when you make changes and updates, old commits are still there and accessible
- Old values are preserved
- First developed as 'imperative data structures'
- Pure functions
From Eric Elliot:
- Given the same input, will always return the same output.
- Produces no side effects.
- You MUST return something
- Why would you need immutable state?
- (from Dan) there's less guesswork involved tracing how data came to be in any given state...
- so errors due to invalid object state should be impossible or easier to isolate for
- some immutable libs/tooling let you view your state changes over time, almost like time-travel debugging
- Instead of Immutable, consider Immer
- Advantages of Persistent Data Structures
- minimum copying
- compact history
- fast comparison
- The library is called 'immutable' because it never changes data, it creates a new new set of data with the changes you've applied
- Lists are called 'stacks' in Immutable.js