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;; --------------------------------------------------------
;; 3.3-pay
;; --------------------------------------------------------
;; define a function named pay that takes parameters from, to, and amount
(defun pay (from to amount)
;; use with-read to view the payments-table of the account from. bind the balance and keyset of this account to from-bal and keyset
(with-read payments-table from { "balance":= from-bal, "keyset":= keyset }
;; enforce that the keyset is the keyset of the account
(enforce-keyset keyset)
;; use with-read to view the balance of the to-bank account. bind this balance to a variable named to-bank-bal
(with-read payments-table to { "balance":= to-bal }
;; enforce that the amount being transferred is greater than 0
(enforce (> amount 0.0) "Negative Transaction Amount")
;; enforce that the balance of the user transferring value is greater than what is being transferred
(enforce (>= from-bal amount) "Insufficient Funds")
;; update payments-table to reflect the new balance of the from account.
(update payments-table from
{ "balance": (- from-bal amount) })
;; update the payments-table to reflect the new balance of the to-bal account.
(update payments-table to
{ "balance": (+ to-bal amount) })
;; return a formatted string to say that the from account has paid the to account the amount paid
(format "{} paid {} {}" [from to amount]))))
)
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