47 lines
1.7 KiB
Racket
47 lines
1.7 KiB
Racket
#lang syndicate
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;; Illustrates the response of asserted / retracted / during to
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;; observation of assertions discarding some of their dimensions.
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(struct ready (what) #:prefab)
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(struct entry (key val) #:prefab)
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(spawn (assert (ready 'listener))
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(on (asserted (entry $key _))
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(log-info "key ~v asserted" key)
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(until (retracted (entry key _))
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(on (asserted (entry key $value))
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(log-info "add binding: ~v -> ~v" key value))
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(on (retracted (entry key $value))
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(log-info "del binding: ~v -> ~v" key value)))
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(log-info "key ~v retracted" key)))
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(spawn (assert (ready 'other-listener))
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(during (entry $key _)
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(log-info "(other-listener) key ~v asserted" key)
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(on-stop (log-info "(other-listener) key ~v retracted" key))
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(during (entry key $value)
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(log-info "(other-listener) ~v ---> ~v" key value)
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(on-stop (log-info "(other-listener) ~v -/-> ~v" key value)))))
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(define (pause)
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(log-info "pause")
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(define token (gensym 'pause)) ;; FIXME:: If we use the same token every time, need epochs!
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(until (asserted (ready token))
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(assert (ready token))))
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(spawn* (until (asserted (ready 'listener)))
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(until (asserted (ready 'other-listener)))
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(assert! (entry 'a 1))
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(assert! (entry 'a 2))
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(assert! (entry 'b 3))
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(assert! (entry 'c 33))
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(assert! (entry 'a 4))
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(assert! (entry 'a 5))
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(pause)
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(retract! (entry 'a 2))
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(retract! (entry 'c 33))
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(assert! (entry 'a 9))
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(pause)
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(retract! (entry 'a ?))
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(pause))
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