giles e200935698 scheme: Phase 10 — quasiquote runtime + 10 tests [shapes-reflective] ...

eval.sx adds quasiquote / unquote / unquote-splicing as syntactic
operators with the canonical R7RS walker:

- (quasiquote X) — top-level entry to scm-quasi-walk
- (unquote X) — at depth-0, evaluates X in env
- (unquote-splicing X) — inside a list, splices X's list value
- Reader-macro sugar: `X / ,X / ,@X work via Phase 1 parser

Algorithm identical to lib/kernel/runtime.sx's knl-quasi-walk:
- Walk template recursively
- Non-list: pass through
- ($unquote/unquote X) head form: eval X
- Inside a list, ($unquote-splicing/unquote-splicing X) head:
  eval X, splice list into surrounding context
- Otherwise: recurse on each element

No depth-tracking yet — nested quasiquotes are not properly
handled (matches Kernel's deferred state).

10 tests: plain atom/list, unquote substitution, splicing at
start/middle/end, nested list with unquote, unquote evaluates
expression, error on non-list splice, error on bare unquote.

**Second consumer for lib/guest/reflective/quoting.sx unlocked.**
Both Kernel and Scheme have structurally identical walkers; the
extraction would parameterise just the unquote/splicing keyword
names (Kernel uses $unquote / $unquote-splicing; Scheme uses
unquote / unquote-splicing — pure cfg, no algorithmic change).

280 total Scheme tests (62+23+49+78+25+20+13+10).

Three reflective-kit extractions unlocked in this Scheme port:
- env.sx        — Phase 2 (consumed directly, third overall consumer)
- evaluator.sx  — Phase 7 (second consumer via eval/interaction-env)
- quoting.sx    — Phase 10 (second consumer via scm-quasi-walk)

The kit extractions themselves remain follow-on commits when
desired. hygiene.sx still awaits a real second consumer
(Scheme phase 6c with scope-set algorithm).

2026-05-14 06:47:51 +00:00

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