Method nat_offset_or_zero

crates/kernel/src/whnf.rs:1180–1190

(
    &mut self,
    e: &KExpr<M>,
    depth: u16,
  )

        continue;
      }

      // Native/string primitives must run before projection-definition
      // rewriting. In the compiled environment, wrappers such as
      // `Subtype.val` and `String.toByteArray` are projection definitions;
      // once rewritten to `Prj`, the cheap primitive recognizers no longer
      // see the original head.
      if family == PrimFamily::Native
        && let Some(reduced) = self.try_reduce_native(&cur)?
      {
        cur = reduced;
        continue;
      }

      // String literal primitives.