#[derive(Debug)]
pub struct WithLocation<T> {
    value: T,
    location: (usize, usize),
}

impl<T> WithLocation<T> {
    pub fn new(value: T, start: usize, end: usize) -> WithLocation<T> {
        WithLocation {
            value: value,
            location: (start, end),
        }
    }

    pub fn map<U, F: FnOnce(T) -> U>(self, f: F) -> WithLocation<U> {
        WithLocation {
            value: f(self.value),
            location: self.location,
        }
    }
}

#[derive(Debug)]
pub struct Program(pub Box<WithLocation<Expression>>);

#[derive(Debug)]
pub enum Expression {
    Number(u64),
}