49 lines
1.5 KiB
Racket
49 lines
1.5 KiB
Racket
#lang typed/syndicate
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(define-type-alias ds-type
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(U (Tuple String Int)
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(Observe (Tuple String ★))
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(Observe (Observe (Tuple String ★)))))
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(dataspace ds-type
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(spawn ds-type
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(facet _
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(fields [balance Int 0])
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(assert (tuple "balance" (ref balance)))
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(on (asserted (tuple "deposit" (bind amount Int)))
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(set! balance (+ (ref balance) amount)))))
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(spawn ds-type
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(facet _
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(fields)
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(on (asserted (tuple "balance" (bind amount Int)))
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(displayln amount))))
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(spawn ds-type
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(facet _
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(fields)
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(on (asserted (observe (tuple "deposit" discard)))
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(facet _
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(fields)
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(assert (tuple "deposit" 100))
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(assert (tuple "deposit" -30)))))))
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#|
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;; Hello-worldish "bank account" example.
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(struct account (balance) #:prefab)
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(struct deposit (amount) #:prefab)
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(spawn (field [balance 0])
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(assert (account (balance)))
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(on (message (deposit $amount))
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(balance (+ (balance) amount))))
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(spawn (on (asserted (account $balance))
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(printf "Balance changed to ~a\n" balance)))
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(spawn* (until (asserted (observe (deposit _))))
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(send! (deposit +100))
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(send! (deposit -30)))
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|# |