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annotate 6-Clojure/banking.clj @ 85:67e2bb3bcccd

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Add bank account processing with refs and dosync calls Also included a "transfer" function to atomically transfer money.
author IBBoard <dev@ibboard.co.uk>
date Sun, 09 Jun 2019 19:47:01 +0100
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67e2bb3bcccd Add bank account processing with refs and dosync calls
IBBoard <dev@ibboard.co.uk>
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1 (def accounts (ref []))
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2
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3 (defn add_account [accts]
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4 (dosync (alter accts conj 0)))
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5
67e2bb3bcccd Add bank account processing with refs and dosync calls
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6 (defn credit [accts acct_num amount]
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7 (dosync
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8 (alter accts assoc acct_num (+ (accts acct_num) amount))
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9 )
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10 )
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11
67e2bb3bcccd Add bank account processing with refs and dosync calls
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12 (defn debit [accts acct_num amount]
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13 (dosync
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14 (alter accts assoc acct_num (- (accts acct_num) amount))
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15 )
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16 )
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18 (defn transfer [accts acct_from acct_to amount]
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19 (dosync
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20 (debit accts acct_from amount)
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21 (credit accts acct_to amount)
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22 )
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23 )
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24
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25 (add_account accounts)
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26 (add_account accounts)
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27 (add_account accounts)
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28 (credit accounts 0 100)
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29 (credit accounts 1 50)
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30 (credit accounts 2 500)
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31 (transfer accounts 2 1 150)
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32 (println @accounts) ; We should get [100, 200, 350]