Why “mutability” is being discussed
The most recent Hacker News stories and comments contributing to this topic's mentions.
Mutability vs immutability describe the relationship between identity and state. Mutable values retain identity when their state changes. For immutable values, getting a new sta…
by barrkel · Sep 20, 2026
No? "Immutable" means "not mutable", so mutability and immutability are mutually exclusive.
by cubefox · Sep 20, 2026
> Types are properties of values, not variables. In statically typed languages, variables and expressions have a compile-time type and values have a run-time type. > Mutability…
by jibal · Sep 20, 2026
> Mutability is a property of variable, not of a value. [...] This has nothing to do with whether it can be reassigned (i.e. mutability). I feel like you're using "mutable" too…
by kaoD · Sep 20, 2026
A system programming language needs to match hardware where mutability is associated with memory addresses, something functional languages can afford to abstract away.
by skew-aberration · Sep 20, 2026
> So from that perspective, interior mutability is a form of rebinding really? i honestly dont have _too_ much experience with functional languages, basically only elixir and co…
by ffsm8 · Sep 20, 2026
Interest
Proportion of Hacker News items mentioning "mutability" over time.
Mentions
Total number of Hacker News items mentioning "mutability" over time.
The principle of mutability is the notion that any physical property which appears to follow a conservation law may undergo some physical process that violates its conservation. John Archibald Wheeler offered this speculative principle after Stephen Hawking predicted the evaporation of black holes which violates baryon number conservation. Read more on Wikipedia