Simple Escrow Contract

Introduction

The contract implements a mechanism of payments to wallets, but instead of doing these payments directly, the lovelaces are blocked in a script, and then each wallet can collect them.

Contract Design

The contract has to store how many lovelaces correspond to each receiver. This information is stored as a map from payment-pubkeyhashes to integers. So, the main, and only, UTxO of the contract contains this map. The creation of this main UTxO is perfomed by the run function that submits a transaction producing the utxo containing the initial state where nobody has lovelaces to collect.

Datums

Main UTxO:

• EscrowState: payments information

Operations

• addPayment: given a payment-pubkeyhash pkh and an integer m, it submits a transaction paying to the script m lovelaces and modifying the state specifying that now pkh has m additional lovelaces.

  

• collect: given a payment-pubkeyhash pkh, it submits a transaction spending the script-utxo and collecting the number of lovelaces specified in the state, corresponding to the pub key pkh signing the transaction. If the transaction can be submitted, the state is modified deleting the map association pkh ↦ m corresponding to the signer.

  

Congestion

The two main operations produce congestion: both of them spend the script main utxo, so only one user can interact with the contract per block.

How to build

Here you can find information about how to build this project and run the on-chain and off-chain tests.

Plutus dependencies

Install the development environment following the official documentation. Once you have all installed, you will start the environment with nix-shell from the plutus repository folder and change into the project folder.

Compilation

$> cabal build

Testing

$> cabal run test

More

You also can load the library or the tests with the repl with cabal repl or cabal repl test.