Simple bank account code

accounts.clj

;;; accounts.clj -- Accounts -*- Clojure -*-
;;; Time-stamp: "2010-05-04 11:17:53 ghoseb"
;;; Author: Baishampayan Ghose <bg@infinitelybeta.com>

(ns accounts)

(def *min-bal* 500)

(defstruct account
  :name
  :balance)


(defn make-account
  "Create a new account"
  [name op-balance]
  ;; op-balance should be stored in a ref so that we can modify it in
  ;; a concurrent manner
  (struct account name (ref op-balance)))


(defn account-balance
  "Get the balance from an account"
  [acc]
  @(:balance acc))


(defn account-holder
  "Get the name of the account holder"
  [acc]
  (:name acc))


(defn deposit
  "Deposit amount into acc"
  [acc amount]
  (dosync
   (commute (:balance acc) + amount)))


(defn withdraw
  "Withdraw amount from acc. Minimum balance is 500"
  [acc amount]
  (dosync
   (let [curr (:balance acc)]
     (if (> (- @curr amount) *min-bal*)
       (alter curr - amount)
       :insufficient-funds))))

(comment

(def *acc (make-account "John Doe" 5000))
(deposit *acc 500)
(account-balance *acc)
(withdraw *acc 20)
(account-balance *acc)

(binding [*min-bal* 0]
  (withdraw *acc 5000))
)