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runtime.sx binds R7RS reflective primitives: - eval EXPR ENV - interaction-environment — returns env captured by closure - null-environment VERSION — fresh empty env (ignores version) - scheme-report-environment N — fresh full standard env - environment? V interaction-environment closes over the standard env being built; each invocation of scheme-standard-env produces a distinct interaction env that returns ITSELF when queried — so user-side (define name expr) inside (eval ... (interaction-environment)) persists for subsequent (eval 'name ...) lookups. 13 tests cover: - eval over quoted forms (literal + constructed via list) - define-then-lookup through interaction-environment - eqv? identity of interaction-environment across calls - sandbox semantics: eval in null-environment errors on + - scheme-report-environment is fresh and distinct from interaction **Second consumer for lib/guest/reflective/evaluator.sx unlocked.** Scheme's eval/interaction-environment/null-environment triple is the same protocol Kernel exposes via eval-applicative / get-current-environment / make-environment. Extraction now satisfies the two-consumer rule — same playbook as env.sx and class-chain.sx, awaits a follow-up commit to actually extract the kit. 270 total Scheme tests (62 + 23 + 49 + 78 + 25 + 20 + 13).
650 lines
20 KiB
Plaintext
650 lines
20 KiB
Plaintext
;; lib/scheme/runtime.sx — R7RS-small standard environment.
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;;
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;; Builds scheme-standard-env from scheme-make-env, populating it with
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;; arithmetic, comparison, type predicates, list/pair/vector/string/char
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;; primitives, and the higher-order combinators (map/filter/fold).
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;;
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;; Primitives are bound as SX fns taking a list of evaluated arguments.
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;; Combinators that re-enter the evaluator (map, filter, fold, apply,
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;; for-each) call `scheme-apply` directly on user-supplied procedures.
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;;
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;; Public API
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;; (scheme-standard-env) — fresh env with the full R7RS-base surface
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;;
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;; Consumes: lib/scheme/eval.sx (scheme-apply, scheme-make-env,
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;; scheme-env-bind!, scheme-string?, scheme-char?,
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;; scheme-vector?, scheme-vector-elements,
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;; scheme-string-value, scheme-char-value,
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;; scheme-string-make, scheme-char-make,
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;; scheme-vector-make).
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;; ── Arity / fold helpers ─────────────────────────────────────────
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(define
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scm-unary
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(fn
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(name f)
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(fn
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(args)
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(cond
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((not (= (length args) 1))
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(error (str name ": expects 1 argument")))
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(:else (f (first args)))))))
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(define
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scm-binary
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(fn
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(name f)
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(fn
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(args)
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(cond
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((not (= (length args) 2))
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(error (str name ": expects 2 arguments")))
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(:else (f (first args) (nth args 1)))))))
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;; Variadic left-fold helper. zero-id is the identity (`(+)` → 0).
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;; one-fn handles single-arg case (`(- x)` negates).
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(define
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scm-fold-step
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(fn
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(f acc rest-args)
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(cond
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((or (nil? rest-args) (= (length rest-args) 0)) acc)
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(:else (scm-fold-step f (f acc (first rest-args)) (rest rest-args))))))
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(define
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scm-fold
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(fn
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(name f zero-id one-fn)
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(fn
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(args)
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(cond
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((= (length args) 0) zero-id)
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((= (length args) 1) (one-fn (first args)))
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(:else (scm-fold-step f (first args) (rest args)))))))
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;; n-ary chained comparison: (< 1 2 3) ≡ (< 1 2) ∧ (< 2 3).
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(define
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scm-chain-step
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(fn
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(cmp prev rest-args)
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(cond
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((or (nil? rest-args) (= (length rest-args) 0)) true)
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(:else
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(let
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((next (first rest-args)))
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(cond
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((cmp prev next) (scm-chain-step cmp next (rest rest-args)))
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(:else false)))))))
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(define
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scm-chain
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(fn
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(name cmp)
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(fn
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(args)
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(cond
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((< (length args) 2)
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(error (str name ": expects at least 2 arguments")))
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(:else (scm-chain-step cmp (first args) (rest args)))))))
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;; ── List helpers ─────────────────────────────────────────────────
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(define
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scm-list-append
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(fn
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(xs ys)
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(cond
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((or (nil? xs) (= (length xs) 0)) ys)
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(:else (cons (first xs) (scm-list-append (rest xs) ys))))))
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(define
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scm-list-reverse-step
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(fn
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(xs acc)
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(cond
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((or (nil? xs) (= (length xs) 0)) acc)
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(:else (scm-list-reverse-step (rest xs) (cons (first xs) acc))))))
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(define
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scm-all-lists?
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(fn
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(xs)
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(cond
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((or (nil? xs) (= (length xs) 0)) true)
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((list? (first xs)) (scm-all-lists? (rest xs)))
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(:else false))))
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(define
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scm-append-all
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(fn
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(lists)
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(cond
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((or (nil? lists) (= (length lists) 0)) (list))
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((= (length lists) 1) (first lists))
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(:else (scm-list-append (first lists) (scm-append-all (rest lists)))))))
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;; ── Map / Filter / Fold ──────────────────────────────────────────
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;; These call scheme-apply directly so closures and primitives both work.
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(define
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scm-map-step
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(fn
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(proc xs)
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(cond
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((or (nil? xs) (= (length xs) 0)) (list))
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(:else
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(cons
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(scheme-apply proc (list (first xs)))
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(scm-map-step proc (rest xs)))))))
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(define
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scm-filter-step
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(fn
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(pred xs)
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(cond
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((or (nil? xs) (= (length xs) 0)) (list))
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(:else
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(let
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((keep? (scheme-apply pred (list (first xs)))))
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(cond
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((not (= keep? false))
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(cons (first xs) (scm-filter-step pred (rest xs))))
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(:else (scm-filter-step pred (rest xs)))))))))
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(define
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scm-fold-left-step
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(fn
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(proc acc xs)
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(cond
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((or (nil? xs) (= (length xs) 0)) acc)
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(:else
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(scm-fold-left-step
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proc
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(scheme-apply proc (list acc (first xs)))
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(rest xs))))))
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(define
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scm-fold-right-step
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(fn
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(proc init xs)
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(cond
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((or (nil? xs) (= (length xs) 0)) init)
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(:else
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(scheme-apply
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proc
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(list (first xs) (scm-fold-right-step proc init (rest xs))))))))
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(define
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scm-for-each-step
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(fn
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(proc xs)
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(cond
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((or (nil? xs) (= (length xs) 0)) nil)
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(:else
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(begin
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(scheme-apply proc (list (first xs)))
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(scm-for-each-step proc (rest xs)))))))
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;; ── Vector helpers ──────────────────────────────────────────────
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(define
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scm-make-vector-step
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(fn
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(n fill acc)
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(cond
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((<= n 0) acc)
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(:else (scm-make-vector-step (- n 1) fill (cons fill acc))))))
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;; ── Standard env ─────────────────────────────────────────────────
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(define
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scheme-standard-env
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(fn
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()
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(let
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((env (scheme-make-env)))
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(scheme-env-bind!
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env
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"+"
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(scm-fold "+" (fn (a b) (+ a b)) 0 (fn (x) x)))
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(scheme-env-bind!
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env
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"-"
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(scm-fold
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"-"
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(fn (a b) (- a b))
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0
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(fn (x) (- 0 x))))
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(scheme-env-bind!
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env
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"*"
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(scm-fold "*" (fn (a b) (* a b)) 1 (fn (x) x)))
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(scheme-env-bind!
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env
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"/"
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(scm-fold
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"/"
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(fn (a b) (/ a b))
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1
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(fn (x) (/ 1 x))))
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(scheme-env-bind!
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env
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"abs"
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(scm-unary
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"abs"
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(fn (n) (if (< n 0) (- 0 n) n))))
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(scheme-env-bind!
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env
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"min"
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(scm-fold "min" (fn (a b) (if (< a b) a b)) nil (fn (x) x)))
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(scheme-env-bind!
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env
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"max"
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(scm-fold "max" (fn (a b) (if (< a b) b a)) nil (fn (x) x)))
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(scheme-env-bind!
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env
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"modulo"
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(scm-binary "modulo" (fn (a b) (- a (* b (floor (/ a b)))))))
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(scheme-env-bind!
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env
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"quotient"
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(scm-binary "quotient" (fn (a b) (floor (/ a b)))))
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(scheme-env-bind!
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env
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"remainder"
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(scm-binary "remainder" (fn (a b) (- a (* b (floor (/ a b)))))))
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(scheme-env-bind!
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env
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"zero?"
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(scm-unary "zero?" (fn (n) (= n 0))))
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(scheme-env-bind!
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env
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"positive?"
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(scm-unary "positive?" (fn (n) (> n 0))))
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(scheme-env-bind!
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env
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"negative?"
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(scm-unary "negative?" (fn (n) (< n 0))))
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(scheme-env-bind! env "=" (scm-chain "=" (fn (a b) (= a b))))
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(scheme-env-bind! env "<" (scm-chain "<" (fn (a b) (< a b))))
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(scheme-env-bind! env ">" (scm-chain ">" (fn (a b) (> a b))))
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(scheme-env-bind! env "<=" (scm-chain "<=" (fn (a b) (<= a b))))
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(scheme-env-bind! env ">=" (scm-chain ">=" (fn (a b) (>= a b))))
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(scheme-env-bind!
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env
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"number?"
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(scm-unary "number?" (fn (v) (number? v))))
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(scheme-env-bind!
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env
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"boolean?"
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(scm-unary "boolean?" (fn (v) (boolean? v))))
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(scheme-env-bind!
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env
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"symbol?"
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(scm-unary "symbol?" (fn (v) (string? v))))
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(scheme-env-bind!
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env
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"string?"
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(scm-unary "string?" (fn (v) (scheme-string? v))))
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(scheme-env-bind!
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env
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"char?"
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(scm-unary "char?" (fn (v) (scheme-char? v))))
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(scheme-env-bind!
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env
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"vector?"
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(scm-unary "vector?" (fn (v) (scheme-vector? v))))
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(scheme-env-bind!
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env
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"null?"
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(scm-unary
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"null?"
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(fn
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(v)
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(or (nil? v) (and (list? v) (= (length v) 0))))))
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(scheme-env-bind!
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env
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"pair?"
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(scm-unary
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"pair?"
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(fn (v) (and (list? v) (> (length v) 0)))))
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(scheme-env-bind!
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env
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"procedure?"
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(scm-unary
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"procedure?"
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(fn
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(v)
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(or
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(callable? v)
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(and (dict? v) (= (get v :scm-tag) :closure))))))
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(scheme-env-bind! env "not" (scm-unary "not" (fn (v) (= v false))))
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(scheme-env-bind!
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env
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"cons"
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(scm-binary "cons" (fn (a b) (cons a b))))
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(scheme-env-bind!
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env
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"car"
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(scm-unary
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"car"
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(fn
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(xs)
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(cond
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((or (nil? xs) (and (list? xs) (= (length xs) 0)))
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(error "car: empty list"))
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(:else (first xs))))))
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(scheme-env-bind!
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env
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"cdr"
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(scm-unary
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"cdr"
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(fn
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(xs)
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(cond
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((or (nil? xs) (and (list? xs) (= (length xs) 0)))
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(error "cdr: empty list"))
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(:else (rest xs))))))
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(scheme-env-bind! env "list" (fn (args) args))
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(scheme-env-bind!
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env
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"length"
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(scm-unary "length" (fn (xs) (length xs))))
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(scheme-env-bind!
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env
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"reverse"
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(scm-unary "reverse" (fn (xs) (scm-list-reverse-step xs (list)))))
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(scheme-env-bind!
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env
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"append"
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(fn
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(args)
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(cond
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((scm-all-lists? args) (scm-append-all args))
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(:else (error "append: all arguments must be lists")))))
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(scheme-env-bind!
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env
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"map"
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(fn
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(args)
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(cond
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((not (= (length args) 2))
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(error "map: expects (proc list)"))
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(:else (scm-map-step (first args) (nth args 1))))))
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(scheme-env-bind!
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env
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"filter"
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(fn
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(args)
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(cond
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((not (= (length args) 2))
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(error "filter: expects (pred list)"))
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(:else (scm-filter-step (first args) (nth args 1))))))
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(scheme-env-bind!
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env
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"fold-left"
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(fn
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(args)
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(cond
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((not (= (length args) 3))
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(error "fold-left: expects (proc init list)"))
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(:else
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(scm-fold-left-step
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(first args)
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(nth args 1)
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(nth args 2))))))
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(scheme-env-bind!
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env
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"fold-right"
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(fn
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(args)
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(cond
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((not (= (length args) 3))
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(error "fold-right: expects (proc init list)"))
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(:else
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(scm-fold-right-step
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(first args)
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(nth args 1)
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(nth args 2))))))
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(scheme-env-bind!
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env
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"for-each"
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(fn
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(args)
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(cond
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((not (= (length args) 2))
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(error "for-each: expects (proc list)"))
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(:else (scm-for-each-step (first args) (nth args 1))))))
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(scheme-env-bind!
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env
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"apply"
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(fn
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(args)
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(cond
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((not (= (length args) 2))
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(error "apply: expects (proc args-list)"))
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(:else (scheme-apply (first args) (nth args 1))))))
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(scheme-env-bind!
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env
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"string-length"
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(scm-unary
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"string-length"
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(fn (s) (string-length (scheme-string-value s)))))
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(scheme-env-bind!
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env
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"string=?"
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(scm-binary
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"string=?"
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(fn (a b) (= (scheme-string-value a) (scheme-string-value b)))))
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(scheme-env-bind!
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env
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"string-append"
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(fn
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(args)
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(scheme-string-make
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(scm-fold-step
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(fn (acc s) (str acc (scheme-string-value s)))
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""
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args))))
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(scheme-env-bind!
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env
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"substring"
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(fn
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(args)
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(cond
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((not (= (length args) 3))
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(error "substring: expects (str start end)"))
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(:else
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(scheme-string-make
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(substring
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(scheme-string-value (first args))
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(nth args 1)
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(nth args 2)))))))
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(scheme-env-bind!
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env
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"char=?"
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(scm-binary
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"char=?"
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(fn (a b) (= (scheme-char-value a) (scheme-char-value b)))))
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(scheme-env-bind! env "vector" (fn (args) (scheme-vector-make args)))
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(scheme-env-bind!
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env
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"vector-length"
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(scm-unary
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"vector-length"
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(fn (v) (length (scheme-vector-elements v)))))
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(scheme-env-bind!
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env
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"vector-ref"
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(scm-binary
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"vector-ref"
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(fn (v i) (nth (scheme-vector-elements v) i))))
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(scheme-env-bind!
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env
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"vector->list"
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(scm-unary "vector->list" (fn (v) (scheme-vector-elements v))))
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(scheme-env-bind!
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env
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"list->vector"
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(scm-unary "list->vector" (fn (xs) (scheme-vector-make xs))))
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(scheme-env-bind!
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env
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"make-vector"
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(fn
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(args)
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(cond
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((= (length args) 1)
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(scheme-vector-make
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(scm-make-vector-step (first args) nil (list))))
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((= (length args) 2)
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(scheme-vector-make
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(scm-make-vector-step
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(first args)
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(nth args 1)
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(list))))
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(:else (error "make-vector: expects (n [fill])")))))
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(scheme-env-bind! env "eqv?" (scm-binary "eqv?" (fn (a b) (= a b))))
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(scheme-env-bind!
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env
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"equal?"
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(scm-binary "equal?" (fn (a b) (= a b))))
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(scheme-env-bind! env "eq?" (scm-binary "eq?" (fn (a b) (= a b))))
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;; ── call/cc (R7RS first-class continuations) ────────────
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;; Captures the host SX continuation, wraps it as a Scheme
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;; procedure (fn (vargs) ...) and passes it to the user proc.
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;; Calling the captured k with one value re-enters the
|
|
;; continuation; with multiple values, passes them as a list.
|
|
(scheme-env-bind! env "call/cc"
|
|
(fn (args)
|
|
(cond
|
|
((not (= (length args) 1))
|
|
(error "call/cc: expects 1 argument"))
|
|
(:else
|
|
(call/cc
|
|
(fn (k)
|
|
(let ((scheme-k
|
|
(fn (vargs)
|
|
(cond
|
|
((= (length vargs) 1) (k (first vargs)))
|
|
(:else (k vargs))))))
|
|
(scheme-apply (first args) (list scheme-k)))))))))
|
|
(scheme-env-bind! env "call-with-current-continuation"
|
|
(refl-env-lookup env "call/cc"))
|
|
;; ── R7RS exception primitives ──────────────────────────
|
|
;; raise V — raises V as exception (host SX raise).
|
|
(scheme-env-bind! env "raise"
|
|
(fn (args)
|
|
(cond
|
|
((not (= (length args) 1))
|
|
(error "raise: expects 1 argument"))
|
|
(:else (raise (first args))))))
|
|
;; error MSG IRRITANTS... — convention: raise an error-object
|
|
;; that's a dict {:scm-error MSG :irritants LIST}. The print
|
|
;; surface (error-object-message / error-object-irritants)
|
|
;; can pull these apart.
|
|
(scheme-env-bind! env "error"
|
|
(fn (args)
|
|
(cond
|
|
((= (length args) 0) (error "error: expects (message [irritant...])"))
|
|
(:else
|
|
(raise {:scm-error (cond
|
|
((scheme-string? (first args))
|
|
(scheme-string-value (first args)))
|
|
(:else (first args)))
|
|
:irritants (rest args)})))))
|
|
(scheme-env-bind! env "error-object?"
|
|
(scm-unary "error-object?"
|
|
(fn (v) (and (dict? v) (string? (get v :scm-error))))))
|
|
(scheme-env-bind! env "error-object-message"
|
|
(scm-unary "error-object-message"
|
|
(fn (v) (scheme-string-make (get v :scm-error)))))
|
|
(scheme-env-bind! env "error-object-irritants"
|
|
(scm-unary "error-object-irritants"
|
|
(fn (v) (get v :irritants))))
|
|
;; with-exception-handler HANDLER THUNK — runs THUNK; if it
|
|
;; raises, calls HANDLER with the raised value (handler can
|
|
;; itself raise or return a value). Implemented via host guard.
|
|
;; with-exception-handler — catch THUNK's raise; if caught,
|
|
;; call HANDLER. If HANDLER itself raises, propagate that to
|
|
;; the outer scope (don't re-catch in this same guard, which
|
|
;; would loop). The two-step outcome-sentinel pattern mirrors
|
|
;; the `guard` special form's escape.
|
|
(scheme-env-bind! env "with-exception-handler"
|
|
(fn (args)
|
|
(cond
|
|
((not (= (length args) 2))
|
|
(error "with-exception-handler: expects 2 arguments"))
|
|
(:else
|
|
(let ((handler (first args))
|
|
(thunk (nth args 1)))
|
|
(let ((outcome
|
|
(guard
|
|
(e (true {:scm-weh-raised true :value e}))
|
|
(scheme-apply thunk (list)))))
|
|
(cond
|
|
((and (dict? outcome) (get outcome :scm-weh-raised))
|
|
(scheme-apply handler (list (get outcome :value))))
|
|
(:else outcome))))))))
|
|
;; ── R7RS reflection: eval / environment accessors ───────
|
|
;; eval EXPR ENV — apply the evaluator to a user-supplied AST.
|
|
(scheme-env-bind! env "eval"
|
|
(fn (args)
|
|
(cond
|
|
((not (= (length args) 2))
|
|
(error "eval: expects (eval expr env)"))
|
|
(:else (scheme-eval (first args) (nth args 1))))))
|
|
;; interaction-environment — the env we're currently building.
|
|
;; The closure captures `env`, so each invocation of
|
|
;; scheme-standard-env produces a distinct interaction env
|
|
;; whose interaction-environment fn returns itself.
|
|
(scheme-env-bind! env "interaction-environment"
|
|
(fn (args)
|
|
(cond
|
|
((not (= (length args) 0))
|
|
(error "interaction-environment: expects 0 args"))
|
|
(:else env))))
|
|
;; null-environment — fresh empty env. R7RS ignores version arg.
|
|
(scheme-env-bind! env "null-environment"
|
|
(fn (args)
|
|
(cond
|
|
((not (= (length args) 1))
|
|
(error "null-environment: expects (version)"))
|
|
(:else (scheme-make-env)))))
|
|
;; scheme-report-environment — fresh full standard env.
|
|
(scheme-env-bind! env "scheme-report-environment"
|
|
(fn (args)
|
|
(cond
|
|
((not (= (length args) 1))
|
|
(error "scheme-report-environment: expects (version)"))
|
|
(:else (scheme-standard-env)))))
|
|
(scheme-env-bind! env "environment?"
|
|
(scm-unary "environment?" (fn (v) (scheme-env? v))))
|
|
;; dynamic-wind BEFORE THUNK AFTER — runs BEFORE, then THUNK,
|
|
;; then AFTER. If THUNK raises, AFTER still runs before the
|
|
;; raise propagates. This is the basic-correctness version;
|
|
;; proper call/cc-escape interaction would need dynamic-extent
|
|
;; tracking, deferred until needed.
|
|
(scheme-env-bind! env "dynamic-wind"
|
|
(fn (args)
|
|
(cond
|
|
((not (= (length args) 3))
|
|
(error "dynamic-wind: expects (before thunk after)"))
|
|
(:else
|
|
(let ((before-thunk (first args))
|
|
(mid-thunk (nth args 1))
|
|
(after-thunk (nth args 2)))
|
|
(begin
|
|
(scheme-apply before-thunk (list))
|
|
(let ((outcome
|
|
(guard
|
|
(e (true {:scm-dw-raised true :value e}))
|
|
(scheme-apply mid-thunk (list)))))
|
|
(begin
|
|
(scheme-apply after-thunk (list))
|
|
(cond
|
|
((and (dict? outcome) (get outcome :scm-dw-raised))
|
|
(raise (get outcome :value)))
|
|
(:else outcome))))))))))
|
|
env)))
|