Spec (eval.sx, primitives.sx):
- Named let: (let loop ((i 0)) body) — self-recursive lambda with TCO
- letrec: mutually recursive local bindings with closure patching
- dynamic-wind: entry/exit guards with wind stack for future continuations
- eq?/eqv?/equal?: identity, atom-value, and deep structural equality
Implementation (evaluator.py, async_eval.py, primitives.py):
- Both sync and async evaluators implement all four forms
- 33 new tests covering all forms including TCO at 10k depth
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
