M10-a-vesting-contract-i

title	M10 - A Vesting Contract I
author	Walker Leite

Introduction

Getting Started

In this module we'll see how to handle time in the blockchain and build a Vesting Contract.

To run this presentation type (you will need nix):

../../slide README.md

Community Support

• LovelaceAcademy Discord
• StackExchange (:bulb: use the tag lovelace-academy)
• Plutonomicon Discord

What you should know

• Bulding smart contracts (module 6);
• Cardano-Transaction-Lib (module 8);

Script Context

Script Context and Purpose

data ScriptContext = ScriptContext
    { scriptContextTxInfo :: TxInfo
      scriptContextPurpose :: ScriptPurpose
    }

data ScriptPurpose =
      Minting CurrencySymbol
    | Spending TxOutRef
    | Rewarding StakingCredential
    | Certifying DCert

data TxOutRef = TxOutRef
    { txOutRefId :: TxId
    , txOutRefIdx :: Integer
    }

data TxId = TxId { getTxId :: BuiltinByteString }

Transaction Info

data TxInfo = TxInfo
    { txInfoInputs :: [TxInInfo]
    , txInfoReferenceInputs :: [TxInInfo]
    , txInfoOutputs :: [TxOut]
    , txInfoFee :: Value
    , txInfoMint :: Value
    , txInfoDCert :: [DCert]
    , txInfoWdrl :: Map StakingCredential Integer   
    , txInfoValidRange :: POSIXTimeRange
    , txInfoSignatories :: [PubKeyHash]
    , txInfoRedeemers :: Map ScriptPurpose Redeemer
    , txInfoData :: Map DatumHash Datum
    , txInfoId :: TxId
    }

Handling Time

Assumptions

• 1 slot = 1 second up to 36 hours (by protocol design)
• Allowed time range can be provided on transaction creation in POSIX format

POSIXTimeRange

type POSIXTimeRange = Interval POSIXTime

newtype POSIXTime = POSIXTime { getPOSIXTime :: Integer }

data Interval a = Interval
    { ivFrom :: LowerBound a
    , ivTo :: UpperBound a
    }

data LowerBound a = LowerBound (Extended a) Closure	
data UpperBound a = UpperBound (Extended a) Closure	

type Closure = Bool

data Extended a = NegInf | Finite a	| PosInf

Deadline

Vesting Contract

• Vesting Contract
• PPP 030304

Breakthrough: Building the Vesting Contract

Description

As a donator I want to lock an ADA value in a contract, to be rewarded to a given beneficiary according a given deadline

As the beneficiary I want to reclaim the locked ADA value only after the deadline

Bootstrap

mkdir modules/M10-a-vesting-contract-i/{contract,dapp}

(
  cd modules/M10-a-vesting-contract-i/contract
  nix flake init -t github:LovelaceAcademy/nix-templates#hor-plutus
)

(
  cd modules/M10-a-vesting-contract-i/dapp
  nix flake init -t github:LovelaceAcademy/nix-templates#pix-ctl-full
)