Data Bus

Disclaimer this feature is experimental, do not use it!

The data bus is an optimization that the backend can use to make recursion more efficient. In order to use it, you must define some inputs of the program entry points (usually the main() function) with the call_data modifier, and the return values with the return_data modifier. These modifiers are incompatible with pub and mut modifiers.

Example

fn main(mut x: u32, y: call_data u32, z: call_data [u32;4] ) -> return_data u32 {
  let a = z[x];
  a+y
}

As a result, both call_data and return_data will be treated as private inputs and encapsulated into a read-only array each, for the backend to process.