Migrating from 0.18 to 1.0

Scalus 1.0.0-M1 is the first milestone of the 1.0 line. Artifact coordinates are unchanged (org.scalus:scalus_3, org.scalus:scalus-cardano-ledger_3, …) – update the version and the compiler plugin together:


libraryDependencies += "org.scalus" %% "scalus" % "1.0.0"
addCompilerPlugin("org.scalus" %% "scalus-plugin" % "1.0.0")

Stability promise

From 1.0.0-M1 onward, scalus-core, scalus-cardano-ledger and scalus-bloxbean-cardano-client-lib are the stable surface, checked with MiMa on every build. Most APIs will stay binary compatible across the 1.x line; some parts will likely still have breaking changes in 1.x releases, always behind a deprecation cycle. scalus-testkit is best-effort; *.internal packages and compiler internals carry no compatibility promise.

On-chain behavior changes

These change generated code, so every script hash changes when you recompile.

Protocol version 11 (van Rossem) is the default compile and evaluation target. Budgets drop roughly 30% and scripts shrink roughly 20%. To reproduce pre-PV11 output for an already deployed contract, use Options.plomin or set targetProtocolVersion = MajorProtocolVersion.plominPV.
BigInt./ and BigInt.% now match Scala semantics (truncated division, quotientInteger/remainderInteger). Previously / compiled to floor division (divideInteger), which differs for negative operands.
Hand-written Eq instances are rejected in on-chain code: === always compiles to structural equality and never calls the instance body. Use Eq.derived for case classes, enums and sealed traits, or wrap a structural comparison in Eq.structural(...).

Removed API

Removed	Use instead
`scalus.compiler.intrinsics.ReprTag`	`scalus.compiler.UplcRepresentation`
`scalus.ScalusDebug`	`scalus.compiler.ScalusDebug`
`scalus.CompileDerivations`	`scalus.compiler.CompileDerivations`
`scalus.serialization.flat` `w7l`	`word7Bytes`
`scalus.bloxbean.TxEvaluator`	`ScalusTransactionEvaluator` or `scalus.cardano.ledger.PlutusScriptEvaluator`
`Builtins.multiIndexArray`	`Builtins.indexArray` per element (it was a Scalus invention no Plutus release implements)

Binary compatibility notes

SIRVersion is 6.0: precompiled .sir artifacts must be recompiled with the 1.0 compiler plugin.
scalus.serialization.flat was converted from a package object to top-level definitions. Scala sources compile unchanged; recompile anything that linked against the old binary names.
Provider traits changed: BlockchainReader.findUtxo/findUtxos moved onto the effect-polymorphic BlockchainReaderTF, which gained an abstract mapF; EmulatorBase gained the applied-transaction log (appliedTxLog, appliedTxIndex, clearAppliedTxs). Custom provider or emulator implementations must implement the new members; users of the built-in providers are unaffected.
ImmutableEmulator and Emulator constructors gained parameters (evaluator mode, transaction log) – use the factory methods rather than the constructors.