Rust predicate AST

predicate_lang.rs

type Input = ();
type Condtion = fn(Input) -> bool;
type Procedure = fn();

#[derive(Clone)]
enum AbstractBoolean {
    And(Box<AbstractBoolean>, Box<AbstractBoolean>),
    Or(Box<AbstractBoolean>, Box<AbstractBoolean>),
    Par(Box<AbstractBoolean>),
    Not(Box<AbstractBoolean>),
    Cond(Condtion),
}

enum AST {
    If(AbstractBoolean, Procedure),
}

fn parseAST(input1: &str) -> Result<Vec<AST>, &str> {
    Err("Not implemented")
}

fn interpret(ast: Vec<AST>) -> Box<dyn Fn(Input)> {
    Box::new(|s| {})
}

fn example(ast: AbstractBoolean) -> Box<dyn Fn(Input) -> bool> {
    Box::new(move |s| match ast.clone() {
        AbstractBoolean::And(lcond, rcond) => example(*lcond)(s) && example(*rcond)(s),
        AbstractBoolean::Or(lcond,rcond) => example(*lcond)(s) || example(*rcond)(s),
        AbstractBoolean::Par(cond) => example(*cond)(s),
        AbstractBoolean::Not(cond) => !example(*cond)(s),
        AbstractBoolean::Cond(fun) => fun(s),
    })
}

TODO :

• Learn more about why the borrow checker hates our example function so much (probably this isn't how to do this)
• Make a better fake input type
• Go learn nom and write an actual parser
• Write some tests