# Vesting Example

By

Travis Horn

Lecture 3, Part 5

Lecture Video

A smart contract you write will have one script address. If deployed, Vesting.hs - which allows people to lock ADA away for specific beneficiaries at specific deadlines - could theoretically be used by millions of people and have millions of UTxOs available to it. When a beneficiary wants to grab ADA out of it, the script must first filter through all of the millions of UTxOs to find the one (or few) that match it.

Parameterizing the contract is a more efficient approach. By parameterizing, the contract code accepts a beneficiary and a deadline as parameters when building the script. This way, each vesting contract is separate. Each is a distinct script with a different script address.!

Source code

Most of my notes for this part are done as comments directly in source code.

My commented code

All of the examples so far have a fixed datum type. In Vesting.hs, the datum type is always...

data VestingDatum = VestingDatum
    { beneficiary :: PaymentPubKeyHash
    , deadline    :: POSIXTime
    } deriving Show

You can parameterize this so that other types of datum can be used. The commented source code above goes much more into detail about this.

With Vesting.hs parameterized and saved as Parameterized.hs, you can try the code out in the Playground.

Set up the simulation almost identically to when we tried out Vesting.hs.

The only difference that you'll see is that the grab endpoint now requires an argument. That argument is the deadline. Wallets now grab UTxOs where they are the beneficiary and the deadline is a specified time.