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ErgoScala compiler

Compiler for Ergo smart contracts written in ErgoScala (a subset of Scala). Compilation from formally verified smart contracts from ergo-contracts is supported.

Usage

  libraryDependencies += "org.ergoplatform" %% "ergo-scala-compiler" % "0.0.0-32-aaadbee1-SNAPSHOT",

Compilation results in producing ErgoContract that provides:

  • ErgoTree instance, Ergo's IR, which is used to define logical propositions protecting boxes (a generalization of coins) in the Ergo blockchain. Serialized ErgoTree expressions are written into UTXO boxes and then evaluated by the transaction verifier;
  • Scala anonymous function that when called with a Context parameter evaluates(reduces) the contract code to a sigma property. It allows us to "call" the contract code without loading up the interpreter.

Example

Contract code in contract call

Ergo contract code can be compiled with ErgoScalaCompiler.contract call:

  import org.ergoplatform.compiler.ErgoScalaCompiler

  def buyerContract(
    tokenId: Coll[Byte],
    tokenAmount: Long,
    buyerPk: SigmaProp
  ): ErgoContract =
    ErgoScalaCompiler.contract {
      buyerPk || {
        (OUTPUTS.nonEmpty && OUTPUTS(0).R4[Coll[Byte]].isDefined) && {
          val tokens = OUTPUTS(0).tokens
          val tokenDataCorrect = tokens.nonEmpty &&
            tokens(0)._1 == tokenId &&
            tokens(0)._2 >= tokenAmount

          val knownId = OUTPUTS(0).R4[Coll[Byte]].get == SELF.id
          tokenDataCorrect && OUTPUTS(0).propositionBytes == buyerPk.propBytes && knownId
        }
      }
    }

Verified contract code in a separate method call

For verified contracts, the compilation is done differently. Formal verification is done using Stainless in ergo-contracts. Verified contract code can be compiled by providing the method call where contract code resides.

  def buyerContractInstance(tokenId: Coll[Byte], tokenAmount: Long, pkA: SigmaProp): ErgoContract =
    ErgoContractCompiler.compile { context: Context =>
      buyer(context, tokenId, tokenAmount, pkA)
    }

see sources

where buyer method holds verified smart contract:

  def buyer(
    ctx: Context,
    tokenId: Coll[Byte],
    tokenAmount: Long,
    buyerPk: SigmaProp
  ): SigmaProp = {
    import ctx._
    buyerPk || {
      (OUTPUTS.nonEmpty && OUTPUTS(0).R4[Coll[Byte]].isDefined) && {
        val tokens = OUTPUTS(0).tokens
        val tokenDataCorrect = tokens.nonEmpty &&
          tokens(0)._1 == tokenId &&
          tokens(0)._2 >= tokenAmount

        val knownId = OUTPUTS(0).R4[Coll[Byte]].get == SELF.id
        tokenDataCorrect &&
        OUTPUTS(0).propositionBytes == buyerPk.propBytes &&
        knownId
      }
    }
  }

see sources