Following #[derive(Interact)], methods to be called from the prompt can be specified by name, along with their parameters, and whether they take in &self or &mut self.

#[interact(mut_fn(function_name(param_a, param_b)))

#[interact(immut_fn(function_name(param_a, param_b)))

For example:

# #![allow(unused_variables)]
#fn main() {
#[derive(Interact)]
#[interact(mut_fn(add(param_a)))]
struct Baz(u32);

impl Baz {
    fn add(&mut self, param_a: u32) {
        self.0 += param_a;
    }
}
#}

The skip attribute allows to make some fields invisible:

#[interact(skip))

The downside is that having any skipped field on a type means that it is unbuildable, and therefore cannot be passed as value to functions or to be assigned using = in an expression.