Thanks for saving me a search, because I was expecting r0 to be hardcoded to zero.
Sometimes hardware is designed with insufficient input from software folks and the result is something asinine like that. That, or some people like watching the world burn.
Not much, but you immediately know it's a function (abstraction).
Besides, the standard notation for the "arrow function" is maplet (x ↦ x + 1) in mathematics. I assume λ notation sees frequent uses in logic and computation theory.
The characters in OP's arrow function have the benefit of being available on a standard keyboard layout. This has proven to be an important syntactic feature, imo.