scheme: Phase 2 evaluator — env.sx third consumer + 23 tests [consumes-env]

lib/scheme/eval.sx — R7RS evaluator skeleton:
- Self-evaluating: numbers, booleans, characters, vectors, strings
- Symbol lookup: refl-env-lookup
- Lists: syntactic-operator table dispatch, else applicative call
- Table-driven syntactic ops (Phase 2 wires `quote` only; full set
  in Phase 3)
- Apply: callable host fn or scheme closure (closure stub for Phase 3)

scheme-make-env / scheme-env-bind! / etc. are THIN ALIASES for the
refl-env-* primitives from lib/guest/reflective/env.sx. No adapter
cfg needed — Scheme's lexical-scope semantics ARE the canonical
wire shape. This is the THIRD CONSUMER for env.sx after Kernel and
Tcl + Smalltalk's variant adapters; the first to use it without
any bridging code. Validates the kit handles canonical-shape
adoption with zero ceremony.

23 tests in lib/scheme/tests/eval.sx cover literals, symbol
lookup with parent-chain shadowing, quote (special form + sugar),
primitive application with nested calls, and an env-as-value
section explicitly demonstrating the kit primitives work on
Scheme envs.

85 total Scheme tests (62 parse + 23 eval).

chisel: consumes-env (third consumer for lib/guest/reflective/env.sx).

lib/scheme/tests/eval.sx

@@ -0,0 +1,162 @@
+;; lib/scheme/tests/eval.sx — exercises lib/scheme/eval.sx (Phase 2).
+
+(define scm-eval-pass 0)
+(define scm-eval-fail 0)
+(define scm-eval-fails (list))
+
+(define
+  scm-eval-test
+  (fn
+    (name actual expected)
+    (if
+      (= actual expected)
+      (set! scm-eval-pass (+ scm-eval-pass 1))
+      (begin
+        (set! scm-eval-fail (+ scm-eval-fail 1))
+        (append! scm-eval-fails {:name name :actual actual :expected expected})))))
+
+(define scm-eval-src (fn (src env) (scheme-eval (scheme-parse src) env)))
+
+;; A toy env with arithmetic + list primitives.
+(define
+  scm-test-env
+  (fn
+    ()
+    (let
+      ((env (scheme-make-env)))
+      (scheme-env-bind!
+        env
+        "+"
+        (fn (args) (+ (first args) (nth args 1))))
+      (scheme-env-bind!
+        env
+        "-"
+        (fn (args) (- (first args) (nth args 1))))
+      (scheme-env-bind!
+        env
+        "*"
+        (fn (args) (* (first args) (nth args 1))))
+      (scheme-env-bind! env "list" (fn (args) args))
+      env)))
+
+;; ── self-evaluating ──────────────────────────────────────────────
+(scm-eval-test
+  "lit: integer"
+  (scm-eval-src "42" (scheme-make-env))
+  42)
+(scm-eval-test "lit: float" (scm-eval-src "3.14" (scheme-make-env)) 3.14)
+(scm-eval-test "lit: #t" (scm-eval-src "#t" (scheme-make-env)) true)
+(scm-eval-test "lit: #f" (scm-eval-src "#f" (scheme-make-env)) false)
+(scm-eval-test
+  "lit: empty list"
+  (scm-eval-src "()" (scheme-make-env))
+  (list))
+(scm-eval-test
+  "lit: string"
+  (scheme-string? (scm-eval-src "\"hello\"" (scheme-make-env)))
+  true)
+(scm-eval-test
+  "lit: char"
+  (scheme-char? (scm-eval-src "#\\a" (scheme-make-env)))
+  true)
+(scm-eval-test
+  "lit: vector"
+  (scheme-vector? (scm-eval-src "#(1 2 3)" (scheme-make-env)))
+  true)
+
+;; ── symbol lookup ────────────────────────────────────────────────
+(scm-eval-test
+  "sym: bound"
+  (let
+    ((env (scheme-make-env)))
+    (scheme-env-bind! env "x" 100)
+    (scm-eval-src "x" env))
+  100)
+(scm-eval-test
+  "sym: parent chain"
+  (let
+    ((p (scheme-make-env)))
+    (scheme-env-bind! p "outer" 1)
+    (let
+      ((c (scheme-extend-env p)))
+      (scheme-env-bind! c "inner" 2)
+      (+ (scm-eval-src "outer" c) (scm-eval-src "inner" c))))
+  3)
+(scm-eval-test
+  "sym: shadowing"
+  (let
+    ((p (scheme-make-env)))
+    (scheme-env-bind! p "x" 1)
+    (let
+      ((c (scheme-extend-env p)))
+      (scheme-env-bind! c "x" 2)
+      (scm-eval-src "x" c)))
+  2)
+
+;; ── quote ────────────────────────────────────────────────────────
+(scm-eval-test
+  "quote: symbol"
+  (scm-eval-src "(quote foo)" (scheme-make-env))
+  "foo")
+(scm-eval-test
+  "quote: list"
+  (scm-eval-src "(quote (+ 1 2))" (scheme-make-env))
+  (list "+" 1 2))
+(scm-eval-test "quote: sugar 'x" (scm-eval-src "'x" (scheme-make-env)) "x")
+(scm-eval-test
+  "quote: sugar list"
+  (scm-eval-src "'(a b c)" (scheme-make-env))
+  (list "a" "b" "c"))
+(scm-eval-test
+  "quote: nested"
+  (scm-eval-src "''x" (scheme-make-env))
+  (list "quote" "x"))
+
+;; ── primitive application ────────────────────────────────────────
+(scm-eval-test "prim: +" (scm-eval-src "(+ 2 3)" (scm-test-env)) 5)
+(scm-eval-test
+  "prim: nested +"
+  (scm-eval-src "(+ (+ 1 2) (+ 3 4))" (scm-test-env))
+  10)
+(scm-eval-test
+  "prim: mixed ops"
+  (scm-eval-src "(- (* 4 5) (+ 3 2))" (scm-test-env))
+  15)
+(scm-eval-test
+  "prim: list builds SX list"
+  (scm-eval-src "(list 1 2 3)" (scm-test-env))
+  (list 1 2 3))
+(scm-eval-test
+  "prim: args eval in order"
+  (let
+    ((env (scm-test-env)))
+    (scheme-env-bind! env "a" 10)
+    (scheme-env-bind! env "b" 20)
+    (scm-eval-src "(+ a b)" env))
+  30)
+
+;; ── env-as-value (the third-consumer demonstration) ─────────────
+;; Scheme's env IS lib/guest/reflective/env.sx's canonical wire shape
+;; with no adapter cfg. Verify the kit primitives work directly.
+(scm-eval-test
+  "env: refl-env? on Scheme env"
+  (refl-env? (scheme-make-env))
+  true)
+(scm-eval-test
+  "env: lookup via kit"
+  (let
+    ((env (scheme-make-env)))
+    (refl-env-bind! env "name" "scheme")
+    (refl-env-lookup env "name"))
+  "scheme")
+(scm-eval-test
+  "env: find-frame walks parent"
+  (let
+    ((p (scheme-make-env)))
+    (refl-env-bind! p "root-binding" 99)
+    (let
+      ((c (scheme-extend-env p)))
+      (= (refl-env-find-frame c "root-binding") p)))
+  true)
+
+(define scm-eval-tests-run! (fn () {:total (+ scm-eval-pass scm-eval-fail) :passed scm-eval-pass :failed scm-eval-fail :fails scm-eval-fails}))