48e2ef5910
Rephrase comments that pointed at deleted Janet files (emit.janet, the seed
sources, 'the Janet back end punts ...') to present-tense descriptions of the
Chez behavior. Comment/docstring-only; the self-host fixpoint is unchanged
(comments don't affect the compiled seed).
Delete five files that were Janet-host shims with no Chez path: clojure.java.io
(provided natively by host/chez/io.ss), and jolt.{nrepl,png,interop,shell}
(the janet.* bridge, os/shell, janet.net — none exist on Chez).
jolt-cf1q.6
216 lines
10 KiB
Scheme
216 lines
10 KiB
Scheme
;; async.ss (jolt-byjr) — clojure.core.async on real OS threads for the Chez host.
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;;
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;; No mature Chez fibers library exists, and this Chez is a threaded build, so a
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;; `go` block is just an OS thread and a channel is a mutex+condition blocking
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;; queue: <! / >! are the blocking <!! / >!! (they "park" by blocking the thread).
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;; <! / >! work ANYWHERE (no CPS transform) —
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;; here because they are ordinary blocking calls. Real parallelism, shared heap.
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;; Trade-off: one OS thread per go block (fine for typical use / conformance, not
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;; for thousands of simultaneous go blocks).
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;;
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;; Channel: an unbuffered channel is a rendezvous (the putter blocks until its
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;; value is taken); a buffered (chan n) put blocks only when full; dropping/sliding
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;; buffers never block the putter. A transducer is applied on the put side.
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;;
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;; The fns are def-var!'d into clojure.core.async; go/go-loop/thread are macros
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;; (mark-macro!) expanding to go-spawn. Loaded after
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;; concurrency.ss (reuses ms->duration). Requires a threaded Chez build.
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;; --- buffers ----------------------------------------------------------------
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(define-record-type async-buffer (fields n kind) (nongenerative async-buffer-v1))
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(define (jolt-async-buffer n) (make-async-buffer n 'fixed))
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(define (jolt-async-dropping-buffer n) (make-async-buffer n 'dropping))
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(define (jolt-async-sliding-buffer n) (make-async-buffer n 'sliding))
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;; --- channels ---------------------------------------------------------------
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;; items: a FIFO list of (value . box); box is #f for a buffered value or a 1-slot
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;; vector for an unbuffered rendezvous put (set #t when taken, waking the putter).
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;; cap 0 + kind 'unbuffered = rendezvous; cap>0 with kind fixed/dropping/sliding.
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(define-record-type async-chan
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(fields mu cv (mutable items) cap kind (mutable closed?) (mutable xrf))
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(nongenerative async-chan-v1))
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(define (ac-qlen ch) (length (async-chan-items ch)))
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(define (ac-qempty? ch) (null? (async-chan-items ch)))
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(define (ac-qpush! ch entry) (async-chan-items-set! ch (append (async-chan-items ch) (list entry))))
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(define (ac-qpop! ch)
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(let ((e (car (async-chan-items ch))))
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(async-chan-items-set! ch (cdr (async-chan-items ch))) e))
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(define (ac-qdrop-oldest! ch) (async-chan-items-set! ch (cdr (async-chan-items ch))))
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;; enqueue honoring the buffer kind (used by the transducer step + buffered puts).
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(define (ac-buf-give! ch v)
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(case (async-chan-kind ch)
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((dropping) (when (< (ac-qlen ch) (async-chan-cap ch)) (ac-qpush! ch (cons v #f))))
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((sliding) (when (>= (ac-qlen ch) (async-chan-cap ch)) (ac-qdrop-oldest! ch))
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(ac-qpush! ch (cons v #f)))
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(else (ac-qpush! ch (cons v #f)))) ; fixed: caller ensured room
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(condition-broadcast (async-chan-cv ch)))
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;; A transducer is a jolt fn (xform); (xform add-rf) yields the channel's reducing
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;; fn. add-rf: 0-arg init, 1-arg completion, 2-arg step (enqueue the output). A
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;; `reduced` step result closes the channel.
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(define (ac-make-add-rf ch)
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(lambda args
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(cond ((null? args) ch) ; init
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((null? (cdr args)) (car args)) ; completion
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(else (ac-buf-give! ch (cadr args)) (car args))))) ; step
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(define (ac-make cap kind xrf) (make-async-chan (make-mutex) (make-condition) '() cap kind #f xrf))
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;; (chan) | (chan n) | (chan buf) | (chan n|buf xform)
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(define (jolt-async-chan . args)
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(let ((buf (if (pair? args) (car args) jolt-nil))
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(xform (if (and (pair? args) (pair? (cdr args))) (cadr args) jolt-nil)))
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(let-values (((cap kind)
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(cond ((async-buffer? buf) (values (async-buffer-n buf) (async-buffer-kind buf)))
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((and (number? buf) (> buf 0)) (values buf 'fixed))
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(else (values 0 'unbuffered)))))
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(let ((ch (ac-make cap kind #f)))
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(unless (jolt-nil? xform)
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(async-chan-xrf-set! ch (jolt-invoke xform (ac-make-add-rf ch))))
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ch))))
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;; close! (idempotent): mark closed, flush a stateful transducer's completion, and
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;; wake everyone. ac-close! assumes the lock is held; the public form takes it.
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(define (ac-close! ch)
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(unless (async-chan-closed? ch)
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(async-chan-closed?-set! ch #t)
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(when (async-chan-xrf ch) (guard (e (#t #f)) (jolt-invoke (async-chan-xrf ch) ch)))
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(condition-broadcast (async-chan-cv ch)))
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jolt-nil)
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(define (jolt-async-close! ch) (with-mutex (async-chan-mu ch) (ac-close! ch)))
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;; >! / >!! — put, blocking. false if closed; nil may not be put. With a
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;; transducer the value is run through it (one put -> zero or more channel values);
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;; a `reduced` result closes the channel.
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(define (jolt-async-give ch v)
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(when (jolt-nil? v) (jolt-throw (jolt-ex-info "Can't put nil on a channel" (jolt-hash-map))))
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(with-mutex (async-chan-mu ch)
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(cond
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((async-chan-closed? ch) #f)
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((async-chan-xrf ch)
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(let ((r (jolt-invoke (async-chan-xrf ch) ch v)))
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(when (jolt-reduced? r) (ac-close! ch))
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#t))
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(else
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(case (async-chan-kind ch)
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((dropping sliding) (ac-buf-give! ch v) #t)
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(else
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(if (> (async-chan-cap ch) 0)
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(let loop () ; buffered fixed: wait for room
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(cond ((async-chan-closed? ch) #f)
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((< (ac-qlen ch) (async-chan-cap ch))
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(ac-qpush! ch (cons v #f)) (condition-broadcast (async-chan-cv ch)) #t)
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(else (condition-wait (async-chan-cv ch) (async-chan-mu ch)) (loop))))
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(let ((box (vector #f))) ; unbuffered: rendezvous
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(ac-qpush! ch (cons v box))
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(condition-broadcast (async-chan-cv ch))
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(let loop ()
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(cond ((vector-ref box 0) #t)
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((async-chan-closed? ch) #f)
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(else (condition-wait (async-chan-cv ch) (async-chan-mu ch)) (loop))))))))))))
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;; remove + return the head value, waking a parked rendezvous putter.
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(define (ac-take-head! ch)
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(let* ((entry (ac-qpop! ch)) (v (car entry)) (box (cdr entry)))
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(when box (vector-set! box 0 #t))
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(condition-broadcast (async-chan-cv ch))
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v))
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;; <! / <!! — take, blocking. Drains buffered values, then nil once closed + empty.
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(define (jolt-async-take ch)
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(with-mutex (async-chan-mu ch)
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(let loop ()
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(cond ((not (ac-qempty? ch)) (ac-take-head! ch))
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((async-chan-closed? ch) jolt-nil)
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(else (condition-wait (async-chan-cv ch) (async-chan-mu ch)) (loop))))))
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;; non-blocking take for alts!: a value, jolt-nil (closed+empty), or ac-poll-empty.
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(define ac-poll-empty (list 'empty))
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(define (ac-poll! ch)
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(with-mutex (async-chan-mu ch)
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(cond ((not (ac-qempty? ch)) (ac-take-head! ch))
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((async-chan-closed? ch) jolt-nil)
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(else ac-poll-empty))))
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;; (alts! [ch ...]) — take from whichever channel is ready first; returns
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;; [value channel] (value nil if that channel closed). Take-only.
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;; Polls with a 1ms backoff — no cross-channel wait-set yet.
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(define ac-1ms (make-time 'time-duration 1000000 0))
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(define (jolt-async-alts chans)
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(let ((cs (seq->list (jolt-seq chans))))
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(let loop ()
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(let try ((rest cs))
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(if (null? rest)
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(begin (sleep ac-1ms) (loop))
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(let ((r (ac-poll! (car rest))))
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(if (eq? r ac-poll-empty)
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(try (cdr rest))
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(jolt-vector r (car rest)))))))))
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;; (timeout ms) — a channel that closes after ms milliseconds.
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(define (jolt-async-timeout ms)
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(let ((w (ac-make 0 'unbuffered #f)))
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(fork-thread (lambda () (sleep (ms->duration ms)) (jolt-async-close! w)))
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w))
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;; (put! ch v [cb]) / (take! ch cb) — async put/take on a thread, optional callback.
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(define (jolt-async-put! ch v . cb)
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(fork-thread (lambda ()
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(let ((ok (jolt-async-give ch v)))
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(when (and (pair? cb) (not (jolt-nil? (car cb)))) (jolt-invoke (car cb) ok)))))
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jolt-nil)
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(define (jolt-async-take! ch cb)
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(fork-thread (lambda ()
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(let ((v (jolt-async-take ch)))
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(unless (jolt-nil? cb) (jolt-invoke cb v)))))
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jolt-nil)
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;; (go-spawn thunk) — run thunk on a thread; return a buffered(1) channel that
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;; conveys its value once then closes (a nil result just closes). Dynamic bindings
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;; are conveyed (Chez inherits the thread-parameter at fork; we install explicitly).
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(define (async-go-spawn thunk)
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(let ((w (ac-make 1 'fixed #f)) (snap (dyn-binding-stack)))
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(fork-thread
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(lambda ()
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(dyn-binding-stack snap)
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(let ((r (guard (e (#t (cons #f e))) (cons #t (jolt-invoke thunk)))))
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(when (and (car r) (not (jolt-nil? (cdr r)))) (jolt-async-give w (cdr r)))
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(jolt-async-close! w))))
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w))
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;; --- macros (expander fns over the reader forms) ----------------------------
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(define cca-go-spawn-sym (jolt-symbol "clojure.core.async" "go-spawn"))
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(define cca-go-sym (jolt-symbol "clojure.core.async" "go"))
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(define cca-fn*-sym (jolt-symbol #f "fn*"))
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(define cca-loop-sym (jolt-symbol #f "loop"))
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;; (go body...) -> (clojure.core.async/go-spawn (fn* [] body...))
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(define (cca-go-macro . body)
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(jolt-list cca-go-spawn-sym (apply jolt-list cca-fn*-sym empty-pvec body)))
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;; (go-loop bindings body...) -> (go (loop bindings body...))
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(define (cca-go-loop-macro bindings . body)
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(jolt-list cca-go-sym (apply jolt-list cca-loop-sym bindings body)))
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;; (thread body...) — a real OS thread (same shape as go here).
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(define (cca-thread-macro . body)
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(jolt-list cca-go-spawn-sym (apply jolt-list cca-fn*-sym empty-pvec body)))
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;; --- install clojure.core.async ---------------------------------------------
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(define (cca-def! name v) (def-var! "clojure.core.async" name v))
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(cca-def! "chan" jolt-async-chan)
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(cca-def! "chan?" async-chan?)
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(cca-def! "buffer" jolt-async-buffer)
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(cca-def! "dropping-buffer" jolt-async-dropping-buffer)
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(cca-def! "sliding-buffer" jolt-async-sliding-buffer)
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(cca-def! "close!" jolt-async-close!)
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(cca-def! "<!" jolt-async-take) (cca-def! "<!!" jolt-async-take)
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(cca-def! ">!" jolt-async-give) (cca-def! ">!!" jolt-async-give)
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(cca-def! "alts!" jolt-async-alts) (cca-def! "alts!!" jolt-async-alts)
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(cca-def! "timeout" jolt-async-timeout)
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(cca-def! "put!" jolt-async-put!)
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(cca-def! "take!" jolt-async-take!)
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(cca-def! "go-spawn" async-go-spawn)
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(cca-def! "go" cca-go-macro) (mark-macro! "clojure.core.async" "go")
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(cca-def! "go-loop" cca-go-loop-macro) (mark-macro! "clojure.core.async" "go-loop")
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(cca-def! "thread" cca-thread-macro) (mark-macro! "clojure.core.async" "thread")
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