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Comments in ground.rkt

This commit is contained in:
Tony Garnock-Jones 2014-06-11 16:21:45 -04:00
parent 4370cb72a4
commit a86da29f68
1 changed files with 22 additions and 0 deletions
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minimart/ground.rkt
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@ -1,4 +1,5 @@
#lang racket/base
;; Breaking the infinite tower of nested Worlds, connecting to the "real" world at the fracture line.
(require racket/async-channel)
(require racket/set)
@ -11,20 +12,36 @@
send-ground-message
run-ground)
;; A GroundEvent is a pair of a Racket (evt?) event and its yielded
;; results.
;; - (event RacketEvent (Listof Any))
(struct event (descriptor values) #:prefab)
;; (Parameterof (Option AsyncChannel))
;; Communication channel from auxiliary (usually driver) threads to
;; the currently-active ground VM.
(define current-ground-event-async-channel (make-parameter #f))
;; Any -> Void
;; Sends a (non-feedback) message at the ground-VM metalevel.
(define (send-ground-message body)
(match (current-ground-event-async-channel)
[(? async-channel? ch) (async-channel-put ch (send body))]
[_ (error 'send-ground-message "Called outside dynamic scope of run-ground")]))
;; RacketEvent -> RacketEvent
;; Wraps a CML-style Racket event with a handler that sends the event
;; results via the ground VM.
(define (event-handler descriptor)
(handle-evt descriptor (lambda vs (send (event descriptor vs)))))
;; CompiledProjection
;; Used to extract event descriptors and results from subscriptions
;; from the ground VM's contained World.
(define event-projection (compile-gestalt-projection (event (?!) ?)))
;; Gestalt -> (Listof RacketEvent)
;; Projects out the active event subscriptions from the given gestalt.
(define (extract-active-events gestalt)
(define es (matcher-key-set (gestalt-project gestalt 0 0 #f event-projection)))
;; TODO: how should the following error be handled, ideally?
@ -36,9 +53,14 @@
(match-define (list e) ev)
(event-handler e)))
;; RacketEvent
;; Used only when the system is not provably inert, in order to let it
;; take further internal reductions.
(define idle-handler
(handle-evt (system-idle-evt) (lambda _ #f)))
;; Action* -> Void
;; Runs a ground VM, booting the outermost World with the given Actions.
(define (run-ground . boot-actions)
(parameterize ((current-ground-event-async-channel (make-async-channel)))
(let await-interrupt ((inert? #f) (p (spawn-world boot-actions)) (active-events '()))