pact1.lisp

;setup environment: module is submitted with keyset definition ...
(env-data { "keyset": { "keys": ["ABCD"] , "pred": "keys-all" } })
;... and is signed by ABCD key
(env-keys "ABCD")

;define keyset to guard module
(define-keyset 'module-keyset (read-keyset "keyset"))

;define smart-contract code
(module payments 'module-keyset

  (defun create-account (id initial-balance)
    "Create a new account for ID with INITIAL-BALANCE funds"
    (insert 'payments-table id { "balance": initial-balance }))

  (defun get-balance (id) (read 'payments-table id 'balance))

  (defun pay-tax (from transfer-amount)
    (let ((to "IRS")
          (amount (* transfer-amount 0.10)))
     (with-read 'payments-table from { "balance":= from-bal }
       (with-read 'payments-table to { "balance":= to-bal }
         (enforce (>= from-bal amount) "Insufficient Funds")
         (update 'payments-table from
                 { "balance": (- from-bal amount) })
         (update 'payments-table to
                 { "balance": (+ to-bal amount) })
         (format "{} paid {} {}" from to amount)))))


  (defun pay (from to amount)            
    (with-read 'payments-table from { "balance":= from-bal }
      (with-read 'payments-table to { "balance":= to-bal }
        (enforce (>= from-bal amount) "Insufficient Funds")
        (pay-tax from amount)
        (update 'payments-table from
                { "balance": (- from-bal amount) })
        (update 'payments-table to
                { "balance": (+ to-bal amount) })
        (format "{} paid {} {}" from to amount))))

)

;define table and "guard" with module
(create-table 'payments-table 'payments)

;create accounts
(create-account "Sarah" 100.25)
(create-account "James" 250.0)
(create-account "IRS" 0.0)

(pay "Sarah" "James" 25.0)

(format "{} {} {}" (get-balance "Sarah") (get-balance "James") (get-balance "IRS"))