pub mod step;
pub mod util;

/// A leaf node for S-Expressions.
///
/// May represent built-in operators,
/// variables (to be added), functions
/// (to be added) or values.
#[derive(Debug)]
#[derive(PartialEq)]
pub enum SLeaf {
    Add,
    Sub,
    Mul,
    Div,
    Int(i32),
}

/// An S-Expression; the defining structure of the language.
#[derive(Debug)]
#[derive(PartialEq)]
pub enum SExp {
    SCons(Box<SExp>, Box<SExp>),
    Atom(SLeaf),
}