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Version: v2.0

Your first transaction.

OK, we've created some coin in Dunshire's central bank. Now it's time to put it to work. When players sign up for our game, they start with a modest sum of coin to help them out. And we've just gotten our first player, benwyatt! Let's get them some coin.

Describing the transaction with Numscript​

Just like before, we're going to use a bit of Numscript to describe the transfer of 100 coin from our central bank to our fist player.

Create a file called first.num with the following Numscript:

send [COIN 100] (
  source = @centralbank
  destination = @player:benwyatt
)

This transaction looks a lot like the one we created earlier:

  • [COIN 100] means we want to send 100 coins. You can send money in whatever currency makes sense for your use case. Very often this will be USD or EUR. (We'll talk more about sending fractions of a unit of currency in a bit).

  • source = @centralbank means the source of the money is the central bank of Dunshire.

  • destination = @player:benwyatt means the money should go to our first player, benwyatt.

info

Account names can contain symbols like :, and so we are using the convention @namespace:owner to create namespaces in our account names. In this case, the account name indicates that it belongs to a player whose in-game username is benwyatt. Of course, you can adopt other conventions as suits your particular needs.

Executing the Numscript​

Once again, we have our transaction described with Numscript, and we are going to execute it against the dunshire ledger.

fctl ledger transactions num first.num

You should see this in response:

ID        | 1
Reference |
Date      | 2022-11-17T11:33:51Z

Source      | Destination     | Asset | Amount
centralbank | player:benwyatt | COIN  | 100

Account         | Asset | Movement | Final balance
centralbank     | COIN  | -100     | 0
player:benwyatt | COIN  | +100     | 100

Metadata : <empty>

And if you visit the Formance dashboard to verify the transaction, clicking on the transactions tab will show:

now we have two transactions

Which shows that the new transaction has been added to the ledger. Click on the ▸ icon next to transaction ID 1 to dig a little deeper:

benwyatt has 100 coin

What happens if we execute it twice?​

The transaction described in first.num can be executed more than once. Let's say we want to send another 100 coin to account @player:benwyatt. We can just execute the same Numscript again. Give it a try:

fctl ledger transactions num first.num

This time, however, we get a different result:

  ERROR   account had insufficient funds

That's because @centralbank had only 100 coin in it to begin with, and we'd already transferred all of that out.

info

Accounts in Formance Ledger cannot go negative! (Except for the special @world account).

info

Transactions described in Numscript are not idempotent by default. Executing the same transaction twice tells Formance Ledger to make two distinct transfers.

Congratulations​

You've now seen the basics of Formance Ledger, and you can:

  • Introduce money into a ledger using the special @world account
  • Create and transfer money between accounts using Numscript
  • Check account existence, balances, and transaction histories using the built-in dashboard