Two fundamental environment bugs fixed:
1. env-set! was used for both binding creation (let, define, params)
and mutation (set!). Binding creation must NOT walk the scope chain
— it should set on the immediate env. Only set! should walk.
Fix: introduce env-bind! for all binding creation. env-set! now
exclusively means "mutate existing binding, walk scope chain".
Changed across spec (eval.sx, cek.sx, render.sx) and all web
adapters (dom, html, sx, async, boot, orchestration, forms).
2. makeLambda/makeComponent/makeMacro/makeIsland used merge(env) to
flatten the closure into a plain object, destroying the prototype
chain. This meant set! inside closures couldn't reach the original
binding — it modified a snapshot copy instead.
Fix: store env directly as closure (no merge). The prototype chain
is preserved, so set! walks up to the original scope.
Tests: 499/516 passing (96.7%), up from 485/516.
Fixed: define self-reference, let scope isolation, set! through
closures, counter-via-closure pattern, recursive functions.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
