Function risk_with 

pub fn risk_with<F>(
    market: &MarketContext,
    tape: &mut Tape<f64>,
    value: F,
) -> Result<(f64, RiskVector), RiskError>
where
    F: for<'a> FnOnce(&MarketView<'a, AReal<f64>>) -> Result<AReal<f64>, PricingError>,

The risk pass. One forward pass, one seed, one reverse sweep, one collection.

The tape is borrowed rather than created, so a caller valuing the same book repeatedly reuses one allocation: Tape::record clears the recording and keeps the buffers, which is what makes a steady-state valuation allocate no tape memory at all.

value is called once. Every trade in a book prices inside that one call, so the sweep count does not depend on how many trades or curves there are — it is one, always.

Errors

RiskError::Pricing if the valuation failed, or the read-back’s own errors.

Panics

Panics if another recording is already open on this thread — recordings do not nest.