Function encode 

pub fn encode(codec: CodecId, expr: &Expr) -> Result<String, Error>

Serialize a data-subset Expr into the codec-neutral portable text form.

codec is used only to tag any error with the calling codec’s id.

Examples

use sim_codec::{decode_portable, encode_portable};
use sim_kernel::{CodecId, Expr};

let expr = Expr::List(vec![Expr::Nil, Expr::Bool(true), Expr::String("hi".into())]);
let text = encode_portable(CodecId(0), &expr).unwrap();
assert_eq!(decode_portable(CodecId(0), &text).unwrap(), expr);

// Eval-only forms are not data and fail closed.
assert!(encode_portable(CodecId(0), &Expr::Block(vec![])).is_err());