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I love Rust but comes from an Ocaml/F# background (and, as others have said, the inspiration is palpable) and you seem to have a common misunderstanding around

I love Rust but comes from an Ocaml/F# background (and, as others have said, the inspiration is palpable) and you seem to have a common misunderstanding around immutable datastructures. Immutable datastructures in functional languages are not datastructures that cannot be mutated, they are datastructure that efficiently produces a new, updated, version on each operation (such as the cons list). While they are slower than traditional datastructure for a typical use case, they tend to be a lot easier to think about, make parallel code much easier and let you easily get back in time to previous versions of your datastructures (when discovering rust, I was actually disapointed that they were not available in the std). The im[0] crate offers what seem to be good Rust implementations of that kind of datastructures (with abetter explanaition of why you would want them). [0]: https://docs.rs/im/13.0.0/im/ https://docs.rs/im/13.0.0/im/

foldr 7y ago
>Immutable datastructures in functional languages are not datastructures that cannot be mutated, This claim seems dubious. But in any case, I think the OP was just talking about immutable data, i.e., in Rust terms, data to which there is no mutable reference. The data in question could be a simple integer.
- nestorD 7y ago
  It seems dubious because the FP community tends to use the expression 'immutable data structures' were 'persistent data structures' would be the proper term. As a matter of fact I have seen data structures, in FP language, called immutable while having operations to mutate them in place. I believe the OP spoke of both Rust immutable data and the fact that most FP languages have only immutable datastructures (different mecanism to deal with similar problems).
  - foldr 7y ago
    I think they were referring to an actual difference between Rust and OCaml, Haskell, etc. Rust allows you to mutate data via mutable references that are guaranteed to be unique. Mainstream functional programming languages do not allow you to do this (though linear typing may land in GHC soon).

foldr 7y ago

>Immutable datastructures in functional languages are not datastructures that cannot be mutated, This claim seems dubious. But in any case, I think the OP was just talking about immutable data, i.e., in Rust terms, data to which there is no mutable reference. The data in question could be a simple integer.

nestorD 7y ago
It seems dubious because the FP community tends to use the expression 'immutable data structures' were 'persistent data structures' would be the proper term. As a matter of fact I have seen data structures, in FP language, called immutable while having operations to mutate them in place. I believe the OP spoke of both Rust immutable data and the fact that most FP languages have only immutable datastructures (different mecanism to deal with similar problems).
- foldr 7y ago
  I think they were referring to an actual difference between Rust and OCaml, Haskell, etc. Rust allows you to mutate data via mutable references that are guaranteed to be unique. Mainstream functional programming languages do not allow you to do this (though linear typing may land in GHC soon).