fn read_from_tokens(tokens: &mut Peekable<Iter<String>>) -> Data {

    if tokens.len() == 0 {
        panic!("Unexpected EOF while parsing.");
    }

    let token = tokens.next().unwrap();

    if token == "(" {
        let mut l = Nil;
        while *tokens.peek().expect("Syntax error! Expected ')'") != ")" {
            l = read_from_tokens(tokens).cons(l);
        }
        tokens.next();
        return l.nreverse();
    }

    match token.parse::<f64>() {
        Ok(f) => return Float(f),
        _ => {;}
    }

    return Symbol(token.to_string())
}
/// Reads an expression from a sequence of tokens.
Reads an expression from a sequence of tokens.
Reads an expression from a sequence of tokens .
fn read_from_tokens(tokens: &mut Peekable<Iter<String>>) -> Data {
    if tokens.len() == 0 {
        panic!("Unexpected EOF while parsing.");
    }
    let token = tokens.next().unwrap();
    if token == "(" {
        let mut l = Nil;
        while *tokens.peek().expect("Syntax error! Expected ')'") != ")" {
            l = read_from_tokens(tokens).cons(l);
        }
        tokens.next();
        return l.nreverse();
    }
    match token.parse::<f64>() {
        Ok(f) => return Float(f),
        _ => {;}
    }
    return Symbol(token.to_string())
}
fn read_from_tokens ( tokens : & mut Peekable < Iter < String > > ) -> Data { if tokens . len ( ) == 0 { panic ! ( " " ) ; } let token = tokens . next ( ) . unwrap ( ) ; if token == " " { let mut l = Nil ; while * tokens . peek ( ) . expect ( " " ) != " " { l = read_from_tokens ( tokens ) . cons ( l ) ; } tokens . next ( ) ; return l . nreverse ( ) ; } match token . parse :: < f64 > ( ) { Ok ( f ) => return Float ( f ) , _ => { ; } } return Symbol ( token . to_string ( ) ) }
Reads an expression from a sequence of tokens.
Reads an expression from a sequence of tokens .
tokens
&mut Peekable<Iter<String>>