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use std::any::Any;
use std::rc::Rc;
pub mod builtin;
mod eval;
mod parse;
pub use eval::{eval_stmt, Env, Fun, FunMut, Pair, Ref, State};
pub fn stringify(x: Rc<dyn Any>) -> Option<String> {
if let Some(_) = x.downcast_ref::<()>() {
return Some("".to_string());
}
if let Some(b) = x.downcast_ref::<bool>() {
return Some(b.to_string());
}
if let Some(n) = x.downcast_ref::<i64>() {
return Some(n.to_string());
}
if let Some(s) = x.downcast_ref::<String>() {
let escaped = s.escape_debug().to_string();
let mut quoted = String::with_capacity(escaped.len() + 2);
quoted.push('"');
quoted.push_str(&escaped);
quoted.push('"');
return Some(quoted);
}
if let Some(r) = x.downcast_ref::<Ref>() {
return Some(r.to_string());
}
if let Some(p) = x.downcast_ref::<Pair>() {
let mut s = String::new();
s.push('(');
stringify_explicit(&mut s, &p.0);
s.push_str(" . ");
stringify_explicit(&mut s, &p.1);
s.push(')');
return Some(s);
}
None
}
fn stringify_explicit(dest: &mut String, x: &Rc<dyn Any>) {
if let Some(_) = x.downcast_ref::<()>() {
dest.push_str("()");
}
if let Some(s) = stringify(x.clone()) {
dest.push_str(&s);
} else {
dest.push('?');
}
}