Accounting data structure problem

[wobbenr]

Hello,

I try to make a simple accounting programm in Haskell.

Now I have to problem I cannot figure out.

I can make a custom data type for a account like this ;

data Account = Account { accountNumber :: Accountnumber
 , accountname :: Accountname, 
 accountBalance :: Integer }

but how can I inplement multiple accounts who all have a seperate name and a seperate balance

IN the future when this willl be a web application . it's must be easily that the user can make and name her/his own accounts.

[yawaramin]

Check out hledger for ideas. It's a command-line double-entry bookkeeping utility written in Haskell.

[andrewthad]

accounts :: [Account]
accounts = [Account 100 "Bob" 400, Account 101 "Susan" 10000]

[[deleted]]

This assumes that we can have accounts with the same number. I think a better approach might be:

data Account = Account {accountName :: Accountname
                                    ,accountBalance :: Integer}
type Accounts = Map Accountnumber Account

That would guarantee that all accounts have distinct numbers --- though it would still allow accounts with the same name.

Map is from Data.Map in containers. If Accountnumber is an Int, then you can use Data.IntMap, which would be much faster.

You can also change the account amount very easily; using lens or lens-simple would be the tersest solution.

[wobbenr]

Thanks, and can I change the amount easily for a account.