[elcritch]

Nim has good stack value support too. Heap vs stack is just treated as more an optimization thing. Rust's borrow checker is most useful for heap memory, not stack.

For stack based values Nim's 'var' and 'openArray[T]' are roughly equivalent to simple implicit lifetimes. I don't know the proper parlance vs more complicated lifetime situations like "capturing" a lifetime.

Its not too different to C++ references either. Sounds like D will also check for similar "lifetime" violations soon as well.

The real difference is heap memory. There Rust's lifetimes allow you to give ownership away. Nim's var parameters can't do that, but instead it gives you fast and cheap non-atomic ref counting. Rusts way does encourage slightly faster code on average at the expense of more effort on programmers.

Whether Rust or Nim, allocations are expensive. Though in my experience Nim's allocator is amazing. It can sometimes be faster to use ref's than stack values.