Compiling Smart Contracts

Basic Compilation

Use PlutusV3.compile to transform your Scala validator into a Plutus script:


import scalus.compiler.Options
import scalus.uplc.PlutusV3
 
// Compile your validator to Plutus V3
val compiled = PlutusV3.compile(MyValidator.validate)
 
// Get the script for use in transactions
val script = compiled.script
val scriptHex = compiled.program.doubleCborHex

The compilation flow: PlutusV3.compile takes a validator entry point and produces a PlutusV3[A] object containing the script, its hash, and address.

Choosing a Plutus Version

Select the appropriate version for your use case:


import scalus.uplc.{PlutusV1, PlutusV2, PlutusV3}
 
// Plutus V3 (recommended for new validators)
val compiledV3 = PlutusV3.compile(MyValidator.validate)
 
// Plutus V2 (for reference inputs, inline datums)
val compiledV2 = PlutusV2.compile(MyValidator.validate)
 
// Plutus V1 (legacy)
val compiledV1 = PlutusV1.compile(MyValidator.validate)

Compilation Options

Control error traces and optimizations via Options:


import scalus.compiler.Options
 
// Development: Include error traces for debugging
given Options = Options.debug
 
// Production: Minimal script size
given Options = Options.release

Options.debug: Adds error location information (easier debugging, larger script)
Options.release: Minimal script size (for production)

You can also enable error traces on a compiled validator:


val compiled = PlutusV3.compile(MyValidator.validate)
 
// Add error traces for debugging
val withTraces = compiled.withErrorTraces

Complete Example


import scalus.*
import scalus.uplc.builtin.Data
import scalus.compiler.Options
import scalus.cardano.onchain.plutus.v3.*
import scalus.uplc.PlutusV3
 
@Compile
object MyValidator {
    inline def validate(scData: Data): Unit = {
        val ctx = scData.to[ScriptContext]
        ctx.scriptInfo match
            case ScriptInfo.SpendingScript(_, datum) =>
                require(ctx.txInfo.signatories.nonEmpty, "No signatories")
            case _ => fail("Must be spending")
    }
}
 
object MyContract {
    private given Options = Options.release
    lazy val compiled = PlutusV3.compile(MyValidator.validate)
}
 
// Get hex for use in transactions
val scriptHex = MyContract.compiled.program.doubleCborHex

Encoding Options

UPLC programs can be encoded in several formats:


val program = compiled.program
 
// Flat encoding (binary format)
val flatEncoded = program.flatEncoded
 
// CBOR encoding (wraps Flat)
val cborEncoded = program.cborEncoded
 
// Double CBOR encoding (standard for Cardano transactions)
val doubleCborEncoded = program.doubleCborEncoded
 
// Hex string of double CBOR (most commonly used in APIs)
val hexString = program.doubleCborHex

What’s Next?

Once your validator compiles, you’re ready to use it in a DApp:

Working with Contract — Set compilation options, generate CIP-57 blueprints, and get script addresses
First Contract Transaction — Lock funds at a script address and spend them with a redeemer
Building Transactions — Build and submit simple ADA transfers using TxBuilder
HTLC Tutorial — End-to-end example: contract, transactions, testing, and deployment