942 lines
34 KiB
Plaintext
942 lines
34 KiB
Plaintext
;; ==========================================================================
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;; eval.sx — Reference SX evaluator written in SX
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;;
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;; This is the canonical specification of SX evaluation semantics.
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;; A thin bootstrap compiler per target reads this file and emits
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;; a native evaluator (JavaScript, Python, Rust, etc.).
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;;
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;; The evaluator is written in a restricted subset of SX:
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;; - defcomp, define, defmacro, lambda/fn
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;; - if, when, cond, case, let, do, and, or
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;; - map, filter, reduce, some, every?
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;; - Primitives: list ops, string ops, arithmetic, predicates
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;; - quote, quasiquote/unquote/splice-unquote
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;; - Pattern matching via (case (type-of expr) ...)
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;;
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;; Platform-specific concerns (DOM rendering, async I/O, HTML emission)
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;; are declared as interfaces — each target provides its own adapter.
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;; ==========================================================================
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;; --------------------------------------------------------------------------
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;; 1. Types
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;; --------------------------------------------------------------------------
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;;
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;; The evaluator operates on these value types:
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;;
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;; number — integer or float
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;; string — double-quoted text
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;; boolean — true / false
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;; nil — singleton null
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;; symbol — unquoted identifier (e.g. div, ~card, map)
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;; keyword — colon-prefixed key (e.g. :class, :id)
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;; list — ordered sequence (also used as code)
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;; dict — string-keyed hash map
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;; lambda — closure: {params, body, closure-env, name?}
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;; macro — AST transformer: {params, rest-param, body, closure-env}
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;; component — UI component: {name, params, has-children, body, closure-env}
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;; thunk — deferred eval for TCO: {expr, env}
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;;
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;; Each target must provide:
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;; (type-of x) → one of the strings above
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;; (make-lambda ...) → platform Lambda value
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;; (make-component ..) → platform Component value
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;; (make-macro ...) → platform Macro value
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;; (make-thunk ...) → platform Thunk value
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;;
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;; These are declared in platform.sx and implemented per target.
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;; --------------------------------------------------------------------------
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;; --------------------------------------------------------------------------
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;; 2. Trampoline — tail-call optimization
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;; --------------------------------------------------------------------------
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(define trampoline
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(fn (val)
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;; Iteratively resolve thunks until we get an actual value.
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;; Each target implements thunk? and thunk-expr/thunk-env.
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(let ((result val))
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(do
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;; Loop while result is a thunk
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;; Note: this is pseudo-iteration — bootstrap compilers convert
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;; this tail-recursive form to a while loop.
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(if (thunk? result)
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(trampoline (eval-expr (thunk-expr result) (thunk-env result)))
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result)))))
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;; --------------------------------------------------------------------------
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;; 3. Core evaluator
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;; --------------------------------------------------------------------------
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(define eval-expr
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(fn (expr env)
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(case (type-of expr)
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;; --- literals pass through ---
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"number" expr
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"string" expr
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"boolean" expr
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"nil" nil
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;; --- symbol lookup ---
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"symbol"
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(let ((name (symbol-name expr)))
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(cond
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(env-has? env name) (env-get env name)
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(primitive? name) (get-primitive name)
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(= name "true") true
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(= name "false") false
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(= name "nil") nil
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:else (error (str "Undefined symbol: " name))))
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;; --- keyword → its string name ---
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"keyword" (keyword-name expr)
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;; --- dict literal ---
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"dict"
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(map-dict (fn (k v) (trampoline (eval-expr v env))) expr)
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;; --- list = call or special form ---
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"list"
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(if (empty? expr)
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(list)
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(eval-list expr env))
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;; --- anything else passes through ---
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:else expr)))
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;; --------------------------------------------------------------------------
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;; 4. List evaluation — dispatch on head
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;; --------------------------------------------------------------------------
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(define eval-list
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(fn (expr env)
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(let ((head (first expr))
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(args (rest expr)))
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;; If head isn't a symbol, lambda, or list → treat as data list
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(if (not (or (= (type-of head) "symbol")
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(= (type-of head) "lambda")
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(= (type-of head) "list")))
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(map (fn (x) (trampoline (eval-expr x env))) expr)
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;; Head is a symbol — check special forms, then function call
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(if (= (type-of head) "symbol")
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(let ((name (symbol-name head)))
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(cond
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;; Special forms
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(= name "if") (sf-if args env)
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(= name "when") (sf-when args env)
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(= name "cond") (sf-cond args env)
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(= name "case") (sf-case args env)
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(= name "and") (sf-and args env)
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(= name "or") (sf-or args env)
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(= name "let") (sf-let args env)
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(= name "let*") (sf-let args env)
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(= name "letrec") (sf-letrec args env)
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(= name "lambda") (sf-lambda args env)
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(= name "fn") (sf-lambda args env)
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(= name "define") (sf-define args env)
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(= name "defcomp") (sf-defcomp args env)
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(= name "defmacro") (sf-defmacro args env)
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(= name "defstyle") (sf-defstyle args env)
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(= name "defkeyframes") (sf-defkeyframes args env)
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(= name "defhandler") (sf-defhandler args env)
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(= name "defpage") (sf-defpage args env)
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(= name "defquery") (sf-defquery args env)
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(= name "defaction") (sf-defaction args env)
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(= name "begin") (sf-begin args env)
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(= name "do") (sf-begin args env)
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(= name "quote") (sf-quote args env)
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(= name "quasiquote") (sf-quasiquote args env)
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(= name "->") (sf-thread-first args env)
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(= name "set!") (sf-set! args env)
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(= name "reset") (sf-reset args env)
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(= name "shift") (sf-shift args env)
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(= name "dynamic-wind") (sf-dynamic-wind args env)
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;; Higher-order forms
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(= name "map") (ho-map args env)
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(= name "map-indexed") (ho-map-indexed args env)
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(= name "filter") (ho-filter args env)
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(= name "reduce") (ho-reduce args env)
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(= name "some") (ho-some args env)
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(= name "every?") (ho-every args env)
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(= name "for-each") (ho-for-each args env)
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;; Macro expansion
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(and (env-has? env name) (macro? (env-get env name)))
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(let ((mac (env-get env name)))
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(make-thunk (expand-macro mac args env) env))
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;; Render expression — delegate to active adapter
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(is-render-expr? expr)
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(render-expr expr env)
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;; Fall through to function call
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:else (eval-call head args env)))
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;; Head is lambda or list — evaluate as function call
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(eval-call head args env))))))
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;; --------------------------------------------------------------------------
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;; 5. Function / lambda / component call
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;; --------------------------------------------------------------------------
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(define eval-call
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(fn (head args env)
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(let ((f (trampoline (eval-expr head env)))
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(evaluated-args (map (fn (a) (trampoline (eval-expr a env))) args)))
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(cond
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;; Native callable (primitive function)
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(and (callable? f) (not (lambda? f)) (not (component? f)))
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(apply f evaluated-args)
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;; Lambda
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(lambda? f)
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(call-lambda f evaluated-args env)
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;; Component
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(component? f)
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(call-component f args env)
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:else (error (str "Not callable: " (inspect f)))))))
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(define call-lambda
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(fn (f args caller-env)
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(let ((params (lambda-params f))
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(local (env-merge (lambda-closure f) caller-env)))
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(if (!= (len args) (len params))
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(error (str (or (lambda-name f) "lambda")
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" expects " (len params) " args, got " (len args)))
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(do
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;; Bind params
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(for-each
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(fn (pair) (env-set! local (first pair) (nth pair 1)))
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(zip params args))
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;; Return thunk for TCO
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(make-thunk (lambda-body f) local))))))
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(define call-component
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(fn (comp raw-args env)
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;; Parse keyword args and children from unevaluated arg list
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(let ((parsed (parse-keyword-args raw-args env))
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(kwargs (first parsed))
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(children (nth parsed 1))
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(local (env-merge (component-closure comp) env)))
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;; Bind keyword params
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(for-each
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(fn (p) (env-set! local p (or (dict-get kwargs p) nil)))
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(component-params comp))
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;; Bind children if component accepts them
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(when (component-has-children? comp)
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(env-set! local "children" children))
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;; Return thunk — body evaluated in local env
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(make-thunk (component-body comp) local))))
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(define parse-keyword-args
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(fn (raw-args env)
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;; Walk args: keyword + next-val → kwargs dict, else → children list
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(let ((kwargs (dict))
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(children (list))
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(i 0))
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;; Iterative parse — bootstrap converts to while loop
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(reduce
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(fn (state arg)
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(let ((idx (get state "i"))
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(skip (get state "skip")))
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(if skip
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;; This arg was consumed as a keyword value
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(assoc state "skip" false "i" (inc idx))
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(if (and (= (type-of arg) "keyword")
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(< (inc idx) (len raw-args)))
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;; Keyword: evaluate next arg and store
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(do
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(dict-set! kwargs (keyword-name arg)
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(trampoline (eval-expr (nth raw-args (inc idx)) env)))
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(assoc state "skip" true "i" (inc idx)))
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;; Positional: evaluate and add to children
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(do
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(append! children (trampoline (eval-expr arg env)))
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(assoc state "i" (inc idx)))))))
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(dict "i" 0 "skip" false)
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raw-args)
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(list kwargs children))))
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;; --------------------------------------------------------------------------
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;; 6. Special forms
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;; --------------------------------------------------------------------------
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(define sf-if
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(fn (args env)
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(let ((condition (trampoline (eval-expr (first args) env))))
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(if (and condition (not (nil? condition)))
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(make-thunk (nth args 1) env)
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(if (> (len args) 2)
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(make-thunk (nth args 2) env)
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nil)))))
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(define sf-when
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(fn (args env)
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(let ((condition (trampoline (eval-expr (first args) env))))
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(if (and condition (not (nil? condition)))
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(do
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;; Evaluate all but last for side effects
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(for-each
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(fn (e) (trampoline (eval-expr e env)))
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(slice args 1 (dec (len args))))
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;; Last is tail position
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(make-thunk (last args) env))
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nil))))
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(define sf-cond
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(fn (args env)
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;; Detect scheme-style: first arg is a 2-element list
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(if (and (= (type-of (first args)) "list")
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(= (len (first args)) 2))
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;; Scheme-style: ((test body) ...)
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(sf-cond-scheme args env)
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;; Clojure-style: test body test body ...
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(sf-cond-clojure args env))))
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(define sf-cond-scheme
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(fn (clauses env)
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(if (empty? clauses)
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nil
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(let ((clause (first clauses))
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(test (first clause))
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(body (nth clause 1)))
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(if (or (and (= (type-of test) "symbol")
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(or (= (symbol-name test) "else")
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(= (symbol-name test) ":else")))
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(and (= (type-of test) "keyword")
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(= (keyword-name test) "else")))
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(make-thunk body env)
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(if (trampoline (eval-expr test env))
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(make-thunk body env)
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(sf-cond-scheme (rest clauses) env)))))))
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(define sf-cond-clojure
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(fn (clauses env)
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(if (< (len clauses) 2)
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nil
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(let ((test (first clauses))
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(body (nth clauses 1)))
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(if (or (and (= (type-of test) "keyword") (= (keyword-name test) "else"))
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(and (= (type-of test) "symbol")
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(or (= (symbol-name test) "else")
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(= (symbol-name test) ":else"))))
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(make-thunk body env)
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(if (trampoline (eval-expr test env))
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(make-thunk body env)
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(sf-cond-clojure (slice clauses 2) env)))))))
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(define sf-case
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(fn (args env)
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(let ((match-val (trampoline (eval-expr (first args) env)))
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(clauses (rest args)))
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(sf-case-loop match-val clauses env))))
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(define sf-case-loop
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(fn (match-val clauses env)
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(if (< (len clauses) 2)
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nil
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(let ((test (first clauses))
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(body (nth clauses 1)))
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(if (or (and (= (type-of test) "keyword") (= (keyword-name test) "else"))
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(and (= (type-of test) "symbol")
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(or (= (symbol-name test) "else")
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(= (symbol-name test) ":else"))))
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(make-thunk body env)
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(if (= match-val (trampoline (eval-expr test env)))
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(make-thunk body env)
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(sf-case-loop match-val (slice clauses 2) env)))))))
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(define sf-and
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(fn (args env)
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(if (empty? args)
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true
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(let ((val (trampoline (eval-expr (first args) env))))
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(if (not val)
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val
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(if (= (len args) 1)
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val
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(sf-and (rest args) env)))))))
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(define sf-or
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(fn (args env)
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(if (empty? args)
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false
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(let ((val (trampoline (eval-expr (first args) env))))
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(if val
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val
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(sf-or (rest args) env))))))
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(define sf-let
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(fn (args env)
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;; Detect named let: (let name ((x 0) ...) body)
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;; If first arg is a symbol, delegate to sf-named-let.
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(if (= (type-of (first args)) "symbol")
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(sf-named-let args env)
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(let ((bindings (first args))
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(body (rest args))
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(local (env-extend env)))
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;; Parse bindings — support both ((name val) ...) and (name val name val ...)
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(if (and (= (type-of (first bindings)) "list")
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(= (len (first bindings)) 2))
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;; Scheme-style
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(for-each
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(fn (binding)
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(let ((vname (if (= (type-of (first binding)) "symbol")
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(symbol-name (first binding))
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(first binding))))
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(env-set! local vname (trampoline (eval-expr (nth binding 1) local)))))
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bindings)
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;; Clojure-style
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(let ((i 0))
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(reduce
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(fn (acc pair-idx)
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(let ((vname (if (= (type-of (nth bindings (* pair-idx 2))) "symbol")
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(symbol-name (nth bindings (* pair-idx 2)))
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(nth bindings (* pair-idx 2))))
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(val-expr (nth bindings (inc (* pair-idx 2)))))
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(env-set! local vname (trampoline (eval-expr val-expr local)))))
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nil
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(range 0 (/ (len bindings) 2)))))
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;; Evaluate body — last expression in tail position
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(for-each
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(fn (e) (trampoline (eval-expr e local)))
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(slice body 0 (dec (len body))))
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(make-thunk (last body) local)))))
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;; Named let: (let name ((x 0) (y 1)) body...)
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;; Desugars to a self-recursive lambda called with initial values.
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;; The loop name is bound in the body so recursive calls produce TCO thunks.
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(define sf-named-let
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(fn (args env)
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(let ((loop-name (symbol-name (first args)))
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(bindings (nth args 1))
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(body (slice args 2))
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(params (list))
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(inits (list)))
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;; Extract param names and init expressions
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(if (and (= (type-of (first bindings)) "list")
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(= (len (first bindings)) 2))
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;; Scheme-style: ((x 0) (y 1))
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(for-each
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(fn (binding)
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(append! params (if (= (type-of (first binding)) "symbol")
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(symbol-name (first binding))
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(first binding)))
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(append! inits (nth binding 1)))
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bindings)
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;; Clojure-style: (x 0 y 1)
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(reduce
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(fn (acc pair-idx)
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(do
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(append! params (if (= (type-of (nth bindings (* pair-idx 2))) "symbol")
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(symbol-name (nth bindings (* pair-idx 2)))
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(nth bindings (* pair-idx 2))))
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(append! inits (nth bindings (inc (* pair-idx 2))))))
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nil
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(range 0 (/ (len bindings) 2))))
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;; Build loop body (wrap in begin if multiple exprs)
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(let ((loop-body (if (= (len body) 1) (first body)
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(cons (make-symbol "begin") body)))
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(loop-fn (make-lambda params loop-body env)))
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;; Self-reference: loop can call itself by name
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(set-lambda-name! loop-fn loop-name)
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(env-set! (lambda-closure loop-fn) loop-name loop-fn)
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;; Evaluate initial values in enclosing env, then call
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(let ((init-vals (map (fn (e) (trampoline (eval-expr e env))) inits)))
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(call-lambda loop-fn init-vals env))))))
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(define sf-lambda
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(fn (args env)
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(let ((params-expr (first args))
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(body (nth args 1))
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(param-names (map (fn (p)
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(if (= (type-of p) "symbol")
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(symbol-name p)
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p))
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params-expr)))
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(make-lambda param-names body env))))
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(define sf-define
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(fn (args env)
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(let ((name-sym (first args))
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(value (trampoline (eval-expr (nth args 1) env))))
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(when (and (lambda? value) (nil? (lambda-name value)))
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(set-lambda-name! value (symbol-name name-sym)))
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(env-set! env (symbol-name name-sym) value)
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value)))
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(define sf-defcomp
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(fn (args env)
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(let ((name-sym (first args))
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(params-raw (nth args 1))
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(body (nth args 2))
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(comp-name (strip-prefix (symbol-name name-sym) "~"))
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(parsed (parse-comp-params params-raw))
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(params (first parsed))
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(has-children (nth parsed 1)))
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(let ((comp (make-component comp-name params has-children body env)))
|
|
(env-set! env (symbol-name name-sym) comp)
|
|
comp))))
|
|
|
|
(define parse-comp-params
|
|
(fn (params-expr)
|
|
;; Parse (&key param1 param2 &children) → (params has-children)
|
|
;; Also accepts &rest as synonym for &children.
|
|
(let ((params (list))
|
|
(has-children false)
|
|
(in-key false))
|
|
(for-each
|
|
(fn (p)
|
|
(when (= (type-of p) "symbol")
|
|
(let ((name (symbol-name p)))
|
|
(cond
|
|
(= name "&key") (set! in-key true)
|
|
(= name "&rest") (set! has-children true)
|
|
(= name "&children") (set! has-children true)
|
|
has-children nil ;; skip params after &children/&rest
|
|
in-key (append! params name)
|
|
:else (append! params name)))))
|
|
params-expr)
|
|
(list params has-children))))
|
|
|
|
|
|
(define sf-defmacro
|
|
(fn (args env)
|
|
(let ((name-sym (first args))
|
|
(params-raw (nth args 1))
|
|
(body (nth args 2))
|
|
(parsed (parse-macro-params params-raw))
|
|
(params (first parsed))
|
|
(rest-param (nth parsed 1)))
|
|
(let ((mac (make-macro params rest-param body env (symbol-name name-sym))))
|
|
(env-set! env (symbol-name name-sym) mac)
|
|
mac))))
|
|
|
|
(define parse-macro-params
|
|
(fn (params-expr)
|
|
;; Parse (a b &rest rest) → ((a b) rest)
|
|
(let ((params (list))
|
|
(rest-param nil))
|
|
(reduce
|
|
(fn (state p)
|
|
(if (and (= (type-of p) "symbol") (= (symbol-name p) "&rest"))
|
|
(assoc state "in-rest" true)
|
|
(if (get state "in-rest")
|
|
(do (set! rest-param (if (= (type-of p) "symbol")
|
|
(symbol-name p) p))
|
|
state)
|
|
(do (append! params (if (= (type-of p) "symbol")
|
|
(symbol-name p) p))
|
|
state))))
|
|
(dict "in-rest" false)
|
|
params-expr)
|
|
(list params rest-param))))
|
|
|
|
|
|
(define sf-defstyle
|
|
(fn (args env)
|
|
;; (defstyle name expr) — bind name to evaluated expr (typically a StyleValue)
|
|
(let ((name-sym (first args))
|
|
(value (trampoline (eval-expr (nth args 1) env))))
|
|
(env-set! env (symbol-name name-sym) value)
|
|
value)))
|
|
|
|
|
|
(define sf-defkeyframes
|
|
(fn (args env)
|
|
;; (defkeyframes name (selector body) ...) — build @keyframes rule,
|
|
;; register in keyframes dict, return StyleValue.
|
|
;; Delegates to platform: build-keyframes returns a StyleValue.
|
|
(let ((kf-name (symbol-name (first args)))
|
|
(steps (rest args)))
|
|
(build-keyframes kf-name steps env))))
|
|
|
|
|
|
(define sf-begin
|
|
(fn (args env)
|
|
(if (empty? args)
|
|
nil
|
|
(do
|
|
(for-each
|
|
(fn (e) (trampoline (eval-expr e env)))
|
|
(slice args 0 (dec (len args))))
|
|
(make-thunk (last args) env)))))
|
|
|
|
|
|
(define sf-quote
|
|
(fn (args env)
|
|
(if (empty? args) nil (first args))))
|
|
|
|
|
|
(define sf-quasiquote
|
|
(fn (args env)
|
|
(qq-expand (first args) env)))
|
|
|
|
(define qq-expand
|
|
(fn (template env)
|
|
(if (not (= (type-of template) "list"))
|
|
template
|
|
(if (empty? template)
|
|
(list)
|
|
(let ((head (first template)))
|
|
(if (and (= (type-of head) "symbol") (= (symbol-name head) "unquote"))
|
|
(trampoline (eval-expr (nth template 1) env))
|
|
;; Walk children, handling splice-unquote
|
|
(reduce
|
|
(fn (result item)
|
|
(if (and (= (type-of item) "list")
|
|
(= (len item) 2)
|
|
(= (type-of (first item)) "symbol")
|
|
(= (symbol-name (first item)) "splice-unquote"))
|
|
(let ((spliced (trampoline (eval-expr (nth item 1) env))))
|
|
(if (= (type-of spliced) "list")
|
|
(concat result spliced)
|
|
(if (nil? spliced) result (append result spliced))))
|
|
(append result (qq-expand item env))))
|
|
(list)
|
|
template)))))))
|
|
|
|
|
|
(define sf-thread-first
|
|
(fn (args env)
|
|
(let ((val (trampoline (eval-expr (first args) env))))
|
|
(reduce
|
|
(fn (result form)
|
|
(if (= (type-of form) "list")
|
|
(let ((f (trampoline (eval-expr (first form) env)))
|
|
(rest-args (map (fn (a) (trampoline (eval-expr a env)))
|
|
(rest form)))
|
|
(all-args (cons result rest-args)))
|
|
(cond
|
|
(and (callable? f) (not (lambda? f)))
|
|
(apply f all-args)
|
|
(lambda? f)
|
|
(trampoline (call-lambda f all-args env))
|
|
:else (error (str "-> form not callable: " (inspect f)))))
|
|
(let ((f (trampoline (eval-expr form env))))
|
|
(cond
|
|
(and (callable? f) (not (lambda? f)))
|
|
(f result)
|
|
(lambda? f)
|
|
(trampoline (call-lambda f (list result) env))
|
|
:else (error (str "-> form not callable: " (inspect f)))))))
|
|
val
|
|
(rest args)))))
|
|
|
|
|
|
(define sf-set!
|
|
(fn (args env)
|
|
(let ((name (symbol-name (first args)))
|
|
(value (trampoline (eval-expr (nth args 1) env))))
|
|
(env-set! env name value)
|
|
value)))
|
|
|
|
|
|
;; --------------------------------------------------------------------------
|
|
;; 6c. letrec — mutually recursive local bindings
|
|
;; --------------------------------------------------------------------------
|
|
;;
|
|
;; (letrec ((even? (fn (n) (if (= n 0) true (odd? (- n 1)))))
|
|
;; (odd? (fn (n) (if (= n 0) false (even? (- n 1))))))
|
|
;; (even? 10))
|
|
;;
|
|
;; All bindings are first set to nil in the local env, then all values
|
|
;; are evaluated (so they can see each other's names), then lambda
|
|
;; closures are patched to include the final bindings.
|
|
;; --------------------------------------------------------------------------
|
|
|
|
(define sf-letrec
|
|
(fn (args env)
|
|
(let ((bindings (first args))
|
|
(body (rest args))
|
|
(local (env-extend env))
|
|
(names (list))
|
|
(val-exprs (list)))
|
|
;; First pass: bind all names to nil
|
|
(if (and (= (type-of (first bindings)) "list")
|
|
(= (len (first bindings)) 2))
|
|
;; Scheme-style
|
|
(for-each
|
|
(fn (binding)
|
|
(let ((vname (if (= (type-of (first binding)) "symbol")
|
|
(symbol-name (first binding))
|
|
(first binding))))
|
|
(append! names vname)
|
|
(append! val-exprs (nth binding 1))
|
|
(env-set! local vname nil)))
|
|
bindings)
|
|
;; Clojure-style
|
|
(reduce
|
|
(fn (acc pair-idx)
|
|
(let ((vname (if (= (type-of (nth bindings (* pair-idx 2))) "symbol")
|
|
(symbol-name (nth bindings (* pair-idx 2)))
|
|
(nth bindings (* pair-idx 2))))
|
|
(val-expr (nth bindings (inc (* pair-idx 2)))))
|
|
(append! names vname)
|
|
(append! val-exprs val-expr)
|
|
(env-set! local vname nil)))
|
|
nil
|
|
(range 0 (/ (len bindings) 2))))
|
|
;; Second pass: evaluate values (they can see each other's names)
|
|
(let ((values (map (fn (e) (trampoline (eval-expr e local))) val-exprs)))
|
|
;; Bind final values
|
|
(for-each
|
|
(fn (pair) (env-set! local (first pair) (nth pair 1)))
|
|
(zip names values))
|
|
;; Patch lambda closures so they see the final bindings
|
|
(for-each
|
|
(fn (val)
|
|
(when (lambda? val)
|
|
(for-each
|
|
(fn (n) (env-set! (lambda-closure val) n (env-get local n)))
|
|
names)))
|
|
values))
|
|
;; Evaluate body
|
|
(for-each
|
|
(fn (e) (trampoline (eval-expr e local)))
|
|
(slice body 0 (dec (len body))))
|
|
(make-thunk (last body) local))))
|
|
|
|
|
|
;; --------------------------------------------------------------------------
|
|
;; 6d. dynamic-wind — entry/exit guards
|
|
;; --------------------------------------------------------------------------
|
|
;;
|
|
;; (dynamic-wind before-thunk body-thunk after-thunk)
|
|
;;
|
|
;; All three are zero-argument functions (thunks):
|
|
;; 1. Call before-thunk
|
|
;; 2. Call body-thunk, capture result
|
|
;; 3. Call after-thunk (always, even on error)
|
|
;; 4. Return body result
|
|
;;
|
|
;; The wind stack is maintained so that when continuations jump across
|
|
;; dynamic-wind boundaries, the correct before/after thunks fire.
|
|
;; Without active continuations, this is equivalent to try/finally.
|
|
;;
|
|
;; Platform requirements:
|
|
;; (push-wind! before after) — push wind record onto stack
|
|
;; (pop-wind!) — pop wind record from stack
|
|
;; (call-thunk f env) — call a zero-arg function
|
|
;; --------------------------------------------------------------------------
|
|
|
|
(define sf-dynamic-wind
|
|
(fn (args env)
|
|
(let ((before (trampoline (eval-expr (first args) env)))
|
|
(body (trampoline (eval-expr (nth args 1) env)))
|
|
(after (trampoline (eval-expr (nth args 2) env))))
|
|
;; Call entry thunk
|
|
(call-thunk before env)
|
|
;; Push wind record, run body, pop, call exit
|
|
(push-wind! before after)
|
|
(let ((result (call-thunk body env)))
|
|
(pop-wind!)
|
|
(call-thunk after env)
|
|
result))))
|
|
|
|
|
|
;; --------------------------------------------------------------------------
|
|
;; 6b. Macro expansion
|
|
;; --------------------------------------------------------------------------
|
|
|
|
(define expand-macro
|
|
(fn (mac raw-args env)
|
|
(let ((local (env-merge (macro-closure mac) env)))
|
|
;; Bind positional params (unevaluated)
|
|
(for-each
|
|
(fn (pair)
|
|
(env-set! local (first pair)
|
|
(if (< (nth pair 1) (len raw-args))
|
|
(nth raw-args (nth pair 1))
|
|
nil)))
|
|
(map-indexed (fn (i p) (list p i)) (macro-params mac)))
|
|
;; Bind &rest param
|
|
(when (macro-rest-param mac)
|
|
(env-set! local (macro-rest-param mac)
|
|
(slice raw-args (len (macro-params mac)))))
|
|
;; Evaluate body → new AST
|
|
(trampoline (eval-expr (macro-body mac) local)))))
|
|
|
|
|
|
;; --------------------------------------------------------------------------
|
|
;; 7. Higher-order forms
|
|
;; --------------------------------------------------------------------------
|
|
|
|
;; call-fn: unified caller for HO forms — handles both Lambda and native callable
|
|
(define call-fn
|
|
(fn (f args env)
|
|
(cond
|
|
(lambda? f) (trampoline (call-lambda f args env))
|
|
(callable? f) (apply f args)
|
|
:else (error (str "Not callable in HO form: " (inspect f))))))
|
|
|
|
(define ho-map
|
|
(fn (args env)
|
|
(let ((f (trampoline (eval-expr (first args) env)))
|
|
(coll (trampoline (eval-expr (nth args 1) env))))
|
|
(map (fn (item) (call-fn f (list item) env)) coll))))
|
|
|
|
(define ho-map-indexed
|
|
(fn (args env)
|
|
(let ((f (trampoline (eval-expr (first args) env)))
|
|
(coll (trampoline (eval-expr (nth args 1) env))))
|
|
(map-indexed
|
|
(fn (i item) (call-fn f (list i item) env))
|
|
coll))))
|
|
|
|
(define ho-filter
|
|
(fn (args env)
|
|
(let ((f (trampoline (eval-expr (first args) env)))
|
|
(coll (trampoline (eval-expr (nth args 1) env))))
|
|
(filter
|
|
(fn (item) (call-fn f (list item) env))
|
|
coll))))
|
|
|
|
(define ho-reduce
|
|
(fn (args env)
|
|
(let ((f (trampoline (eval-expr (first args) env)))
|
|
(init (trampoline (eval-expr (nth args 1) env)))
|
|
(coll (trampoline (eval-expr (nth args 2) env))))
|
|
(reduce
|
|
(fn (acc item) (call-fn f (list acc item) env))
|
|
init
|
|
coll))))
|
|
|
|
(define ho-some
|
|
(fn (args env)
|
|
(let ((f (trampoline (eval-expr (first args) env)))
|
|
(coll (trampoline (eval-expr (nth args 1) env))))
|
|
(some
|
|
(fn (item) (call-fn f (list item) env))
|
|
coll))))
|
|
|
|
(define ho-every
|
|
(fn (args env)
|
|
(let ((f (trampoline (eval-expr (first args) env)))
|
|
(coll (trampoline (eval-expr (nth args 1) env))))
|
|
(every?
|
|
(fn (item) (call-fn f (list item) env))
|
|
coll))))
|
|
|
|
|
|
(define ho-for-each
|
|
(fn (args env)
|
|
(let ((f (trampoline (eval-expr (first args) env)))
|
|
(coll (trampoline (eval-expr (nth args 1) env))))
|
|
(for-each
|
|
(fn (item) (call-fn f (list item) env))
|
|
coll))))
|
|
|
|
|
|
;; --------------------------------------------------------------------------
|
|
;; 8. Primitives — pure functions available in all targets
|
|
;; --------------------------------------------------------------------------
|
|
;; These are the ~80 built-in functions. Each target implements them
|
|
;; natively but they MUST have identical semantics. This section serves
|
|
;; as the specification — bootstrap compilers use it for reference.
|
|
;;
|
|
;; Primitives are NOT defined here as SX lambdas (that would be circular).
|
|
;; Instead, this is a declarative registry that bootstrap compilers read.
|
|
;; --------------------------------------------------------------------------
|
|
|
|
;; See primitives.sx for the full specification.
|
|
|
|
|
|
;; --------------------------------------------------------------------------
|
|
;; 9. Platform interface — must be provided by each target
|
|
;; --------------------------------------------------------------------------
|
|
;;
|
|
;; Type inspection:
|
|
;; (type-of x) → "number" | "string" | "boolean" | "nil"
|
|
;; | "symbol" | "keyword" | "list" | "dict"
|
|
;; | "lambda" | "component" | "macro" | "thunk"
|
|
;; (symbol-name sym) → string
|
|
;; (keyword-name kw) → string
|
|
;;
|
|
;; Constructors:
|
|
;; (make-lambda params body env) → Lambda
|
|
;; (make-component name params has-children body env) → Component
|
|
;; (make-macro params rest-param body env name) → Macro
|
|
;; (make-thunk expr env) → Thunk
|
|
;;
|
|
;; Accessors:
|
|
;; (lambda-params f) → list of strings
|
|
;; (lambda-body f) → expr
|
|
;; (lambda-closure f) → env
|
|
;; (lambda-name f) → string or nil
|
|
;; (set-lambda-name! f n) → void
|
|
;; (component-params c) → list of strings
|
|
;; (component-body c) → expr
|
|
;; (component-closure c) → env
|
|
;; (component-has-children? c) → boolean
|
|
;; (macro-params m) → list of strings
|
|
;; (macro-rest-param m) → string or nil
|
|
;; (macro-body m) → expr
|
|
;; (macro-closure m) → env
|
|
;; (thunk? x) → boolean
|
|
;; (thunk-expr t) → expr
|
|
;; (thunk-env t) → env
|
|
;;
|
|
;; Predicates:
|
|
;; (callable? x) → boolean (native function or lambda)
|
|
;; (lambda? x) → boolean
|
|
;; (component? x) → boolean
|
|
;; (macro? x) → boolean
|
|
;; (primitive? name) → boolean (is name a registered primitive?)
|
|
;; (get-primitive name) → function
|
|
;;
|
|
;; Environment:
|
|
;; (env-has? env name) → boolean
|
|
;; (env-get env name) → value
|
|
;; (env-set! env name val) → void (mutating)
|
|
;; (env-extend env) → new env inheriting from env
|
|
;; (env-merge base overlay) → new env with overlay on top
|
|
;;
|
|
;; Mutation helpers (for parse-keyword-args):
|
|
;; (dict-set! d key val) → void
|
|
;; (dict-get d key) → value or nil
|
|
;; (append! lst val) → void (mutating append)
|
|
;;
|
|
;; Error:
|
|
;; (error msg) → raise/throw with message
|
|
;; (inspect x) → string representation for debugging
|
|
;;
|
|
;; Utility:
|
|
;; (strip-prefix s prefix) → string with prefix removed (or s unchanged)
|
|
;; (apply f args) → call f with args list
|
|
;; (zip lists...) → list of tuples
|
|
;;
|
|
;;
|
|
;; CSSX (style system):
|
|
;; (build-keyframes name steps env) → StyleValue (platform builds @keyframes)
|
|
;;
|
|
;; Dynamic wind (for dynamic-wind):
|
|
;; (push-wind! before after) → void (push wind record onto stack)
|
|
;; (pop-wind!) → void (pop wind record from stack)
|
|
;; (call-thunk f env) → value (call a zero-arg function)
|
|
;; --------------------------------------------------------------------------
|