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concat_lists

sui_eval::value

Function concat_lists 

Source 
pub fn concat_lists(
    left: Value,
    right_elems: &[Value],
) -> Result<Value, EvalError>
Expand description

Concatenate two Nix lists: left ++ right_elems.

left must be a Value::List; right_elems is the right list’s element slice. When left’s backing Rc<Vec> is uniquely owned (a fresh temporary, as in a left-associative acc ++ [x] fold), the right elements are appended IN PLACE — amortized O(1) instead of the O(n) full clone that left.to_vec() would cost. When the Rc is shared, the shared list is left untouched and a fresh clone-extended Vec is built (identical to the prior to_vec() + extend_from_slice path).

§Byte-neutrality

PROVABLY-NEUTRAL. Both paths produce the identical ordered sequence of the same Rc-shared lazy Value thunks — no element is forced, reordered, or re-identified. The only observable difference is heap allocation reuse, which is not a Nix-observable property. See docs/PERF-ARSENAL.md.