How so? This feel distinct from the "algebraic effects"-like features like constness, async, can-panic, can-unwind, etc., since this is a property of the types themselves rather than of functions.

The traits are essentially effect handlers for effects like `drop<T>`, `move<T>`, `forget<T>` which are implicitly charged to the a function which owns a `T` and does drops, moves, or forgets it.

Inferring the capabilities of the function from the traits of the types of the arguments is similar to tracking effects. The function charges `drop<T>` when `x: T` goes out of scope, which is handled by the trait implementation. If Rust had a proper algebraic effects type system, you would be able to see this directly in the signature of the function (and even more, if the trait impls themselves had their effects tracked, you'd be able to see from the signature of the function the side effects of deallocation of its owned variables, like if `drop<File>` performs `io`).