Plutus : Plutus.V1.Ledger Essentials

📌 Table of Contents

1. 📁 What Is Plutus.V1.Ledger?

2. 🧱 Core Modules Breakdown

3. 📬 Working with Addresses

4. 🔐 Working with Signatures & Keys

5. 💰 Working with Values

6. 🧾 Working with Transactions

7. 🧪 Script Contexts & Purpose

8. 🛠 Utilities (Time, Interval, etc.)

9. 🧠 Glossary of Terms

10. 🧪 Validator Script Examples

11. 🔧 Typed Validator Wrappers

12. 🧪 Emulator Trace Integration

---

1️⃣ 📁 What Is Plutus.V1.Ledger?

Plutus.V1.Ledger is a collection of types and utilities from the Plutus smart contract platform used to build secure, type-safe smart contracts for Cardano. It includes definitions for:

• Addresses

• Transactions

• Values

• Script contexts

• Signatures and more

---

2️⃣ 🧱 Core Modules Breakdown

Module	Purpose
Address	Work with Cardano addresses
Value	Represent and manipulate tokens
Tx, TxInfo	Transaction and transaction context
Scripts, ScriptContext	For writing validators
Contexts	Access to signatures, redeemers, datums
Interval, Slot, Time	Handling time and validity ranges

---

3️⃣ 📬 Working with Addresses

import Plutus.V1.Ledger.Address

• Address is either a public key hash or a script hash.

• Use scriptHashAddress to create an address from a validator script hash.

scriptAddr :: ValidatorHash -> Address
scriptAddr = scriptHashAddress

---

4️⃣ 🔐 Working with Signatures & Keys

import Plutus.V1.Ledger.Crypto

• PubKeyHash: Identifies wallets.

• txSignedBy :: TxInfo -> PubKeyHash -> Bool checks if a transaction is signed by a given key.

---

5️⃣ 💰 Working with Values

import Plutus.V1.Ledger.Value

• Value is a map of CurrencySymbol -> TokenName -> Amount.

• Use singleton to construct a token bundle:

ada :: Value
ada = lovelaceValueOf 5000000

• Combine values using +, -, or valueOf.

---

6️⃣ 🧾 Working with Transactions

import Plutus.V1.Ledger.Tx

• TxInfo gives all information about the transaction.

• Key fields:

  • txInfoInputs, txInfoOutputs

  • txInfoSignatories

  • txInfoValidRange

Use it in validators:

{-# INLINABLE mkValidator #-}
mkValidator :: () -> () -> ScriptContext -> Bool
mkValidator _ _ ctx = txSignedBy info somePkh
  where info = scriptContextTxInfo ctx

---

7️⃣ 🧪 Script Contexts & Purpose

import Plutus.V1.Ledger.Contexts

• ScriptContext: Execution context of a Plutus script.

• ScriptPurpose: Why the script is running (e.g., Spending, Minting).

data ScriptPurpose = Spending TxOutRef | Minting CurrencySymbol | ...

• Access redeemer with findOwnInput, findDatum, etc.

---

8️⃣ 🛠 Utilities (Time, Interval, etc.)

import Plutus.V1.Ledger.Interval
import Plutus.V1.Ledger.Time

• Use POSIXTime and POSIXTimeRange for timelocks.

• Example:

validBeforeDeadline :: POSIXTime -> ScriptContext -> Bool
validBeforeDeadline dl ctx = to dl `contains` txInfoValidRange info
  where info = scriptContextTxInfo ctx

---

9️⃣ 🧠 Glossary of Terms

Term	Description
Address	Script or wallet hash for locking funds
Value	Multi-asset bundle of tokens
TxInfo	Transaction information (inputs, signers, outputs)
ScriptContext	Runtime context passed to validators
PubKeyHash	Hash of wallet public key
CurrencySymbol	Identifier for a token type
TokenName	Token label (e.g., "MyCoin")
POSIXTime	UTC time representation
Validator	Script that determines if a transaction is allowed

---

🔟 🧪 Validator Script Examples

🔐 Signature Check Validator

{-# INLINABLE mkSigValidator #-}
mkSigValidator :: PubKeyHash -> () -> () -> ScriptContext -> Bool
mkSigValidator pkh _ _ ctx = txSignedBy (scriptContextTxInfo ctx) pkh

⏰ Timelock Validator

{-# INLINABLE mkTimeValidator #-}
mkTimeValidator :: POSIXTime -> () -> () -> ScriptContext -> Bool
mkTimeValidator deadline _ _ ctx = from deadline `contains` txInfoValidRange (scriptContextTxInfo ctx)

💸 Minimum ADA Sent to Address

{-# INLINABLE mkPaymentValidator #-}
mkPaymentValidator :: Address -> () -> () -> ScriptContext -> Bool
mkPaymentValidator addr _ _ ctx =
  any (\o -> txOutAddress o == addr && lovelaceValueOf (txOutValue o) >= 1000000) $ txInfoOutputs (scriptContextTxInfo ctx)

---

1️⃣1️⃣ 🔧 Typed Validator Wrappers

data Basic
instance Scripts.ValidatorTypes Basic where
    type instance DatumType Basic = ()
    type instance RedeemerType Basic = ()

typedSigValidator :: PubKeyHash -> Scripts.TypedValidator Basic
typedSigValidator pkh = Scripts.mkTypedValidator @Basic
  ($$(PlutusTx.compile [|| mkSigValidator ||]) `PlutusTx.applyCode` PlutusTx.liftCode pkh)
  $$(PlutusTx.compile [|| Scripts.wrapValidator ||])

---

1️⃣2️⃣ 🧪 Emulator Trace Integration

emulatorTraceExample :: EmulatorTrace ()
emulatorTraceExample = do
  let pkh = mockWalletPaymentPubKeyHash $ knownWallet 1
      val = Scripts.validatorScript $ typedSigValidator pkh
      addr = scriptAddress val
  h1 <- activateContractWallet (knownWallet 1) endpoints
  callEndpoint @"lock" h1 (addr, 5000000)
  void $ Emulator.waitNSlots 1

Use this with endpoints for lock/spend via submitTxConstraints.

---

✅ Summary

The Plutus.V1.Ledger module is your toolkit for interacting with the Cardano ledger when writing smart contracts. It provides powerful primitives to:

• Read transaction data

• Check authorization

• Work with tokens and addresses

• Enforce timelocks and intervals