tatara-lisp-eval — runtime evaluator for the tatara-lisp authoring surface.
See docs/eval-design.md in the tatara-lisp repo for scope, FFI surface,
error model, and the boundary with the plain tatara-lisp compile pipeline.
This crate extends tatara-lisp; it does not replace it. The plain Sexp
AST and compile_typed flow remain the fast, committed, cacheable path
for typed infrastructure DSLs. tatara-lisp-eval is for the runtime /
REPL / ad-hoc path — live orchestration, rule evaluation, hot-reloaded
diagnostic bundles.
Phase progress (Phase 2.2 scaffold)
This commit establishes shape: module layout, public types, stub interpreter that evaluates only literal atoms. Subsequent phases (2.3-2.7) fill in special forms, FFI, REPL, errors, tests.