Hacker News Reader

Comment by christianpbrink | Hacker News Reader

I think catnaroek has this right.

Neither that nor my original comment is meant to suggest that it would be straightforward for Rust to borrow from Haskell. Just that the post's comments on Haskell seemed to reflect misconceptions.

View on HN

OTOH, I am not really sure I would want STM in a systems language. It is a little bit too magical, taking into account all the possible retries of a transaction. Perhaps something based on the pi calculus would be a better fit.

I think the magic factor is a key point. Haskell is by design a very high-level language. Things like STM and other "magic monads" allow a lot of stuff to happen under the hood, with guarantees of correctness because of other constraints on the language, but not necessarily a great degree of control of what exactly is happening. Rust, on the other hand, is meant for low-level programming and as such tends to be very explicit about what it's doing at every step. I think Rust and Haskell happen to share some similarities but ultimately they're just not designed for the same purpose. Nothing wrong with learning both :)

Side-note, Idris is a Haskell-inspired pure language which is strict by default. It's designed from the outset to be useful for systems programming, and also has some cool theoretical ideas like dependent types. It might be worth looking into for those who wish Rust was more like Haskell, or vice-versa.

Sadly, AFAIK, Idris does not have linear types out of the box. I am aware that you can prove you are properly releasing your resources using dependent types, so technically speaking there is no loss of expressivity. However, having the compiler do the checking and enforcement automatically is a huge usability win in my book, especially since juggling with the lifetimes of various resources is such a common task in systems programming.

That aside, Idris looks very promising for verified application development.

Reply on news.ycombinator.com