This repo explores a way to abstract over Rc<T> and Arc<T> using the (limited?) capabilities of Rust as it exists at the time of writing this.

The idea is short and simple, that an extra page of description is unnecessary. So please head over to src/lib.rs to read the code and comments.

UPDATE: /u/stevenportzer from reddit kindly pointed out an alternate method that uses a second indirection using traits to avoid making infinite types without losing genericity. If the playground link over there fails to work, here is a copy.

To let the user of a data structure library choose the type of reference counting used internally without duplicating code (or macro gymnastics).

Because Rc is significantly faster than Arc. So if the user is running a single-threaded program, she may not want all the features and over-heads that Arc comes with.