Scala Mill Worked Example
2018-05-03
Earlier this year Mill, a new Scala build tool, was released. It seemed pretty nifty - SBT has been very heavyweight and tends to be slow. I'm looking at using Scala for a home project, and I came up with this Mill build definition. I think it'll prove useful to others. Note that I've tuned it for an essentially "industrial" level of code cleanliness - WartRemover, tons of compile errors, etc. Comments or improvements on this are, of course, appreciated - paul@nathan.house . // -*- mode: Scala; -*-
import mill._
import mill.scalalib._
import coursier.maven.MavenRepository
object project extends ScalaModule {
def scalaVersion = "2.12.6"
def repositories = super.repositories ++ Seq(
MavenRepository("https://oss.sonatype.org/content/repositories/releases")
)
def ivyDeps = Agg(
ivy"com.sparkjava:spark-core:2.7.2",
ivy"io.circe::circe-core:0.9.3",
ivy"io.circe::circe-generic:0.9.3",
ivy"io.circe::circe-parser:0.9.3")
// Keep this code sparkly clean with the POWER OF TYPES.
def compileIvyDeps = Agg(ivy"org.wartremover::wartremover:2.2.1")
def scalacPluginIvyDeps = Agg(ivy"org.wartremover::wartremover:2.2.1")
def mainClass = Some("History.History")
// Mostly mooched from https://tpolecat.github.io/2017/04/25/scalac-flags.html
def scalacOptions = Seq(
// Wart remover!
"-P:wartremover:traverser:org.wartremover.warts.Unsafe",
"-P:wartremover:traverser:org.wartremover.warts.PublicInference",
"-deprecation", // Emit warning and location for usages of deprecated APIs.
"-encoding", "utf-8", // Specify character encoding used by source files.
"-explaintypes", // Explain type errors in more detail.
"-feature", // Emit warning and location for usages of features that should be imported explicitly.
"-language:existentials", // Existential types (besides wildcard types) can be written and inferred
"-language:experimental.macros", // Allow macro definition (besides implementation and application)
"-language:higherKinds", // Allow higher-kinded types
"-language:implicitConversions", // Allow definition of implicit functions called views
"-unchecked", // Enable additional warnings where generated code depends on assumptions.
"-Xcheckinit", // Wrap field accessors to throw an exception on uninitialized access.
"-Xfatal-warnings", // Fail the compilation if there are any warnings.
"-Xfuture", // Turn on future language features.
"-Xlint:adapted-args", // Warn if an argument list is modified to match the receiver.
"-Xlint:by-name-right-associative", // By-name parameter of right associative operator.
"-Xlint:constant", // Evaluation of a constant arithmetic expression results in an error.
"-Xlint:delayedinit-select", // Selecting member of DelayedInit.
"-Xlint:doc-detached", // A Scaladoc comment appears to be detached from its element.
"-Xlint:inaccessible", // Warn about inaccessible types in method signatures.
"-Xlint:infer-any", // Warn when a type argument is inferred to be `Any`.
"-Xlint:missing-interpolator", // A string literal appears to be missing an interpolator id.
"-Xlint:nullary-override", // Warn when non-nullary `def f()' overrides nullary `def f'.
"-Xlint:nullary-unit", // Warn when nullary methods return Unit.
"-Xlint:option-implicit", // Option.apply used implicit view.
"-Xlint:package-object-classes", // Class or object defined in package object.
"-Xlint:poly-implicit-overload", // Parameterized overloaded implicit methods are not visible as view bounds.
"-Xlint:private-shadow", // A private field (or class parameter) shadows a superclass field.
"-Xlint:stars-align", // Pattern sequence wildcard must align with sequence component.
"-Xlint:type-parameter-shadow", // A local type parameter shadows a type already in scope.
"-Xlint:unsound-match", // Pattern match may not be typesafe.
"-Yno-adapted-args", // Do not adapt an argument list (either by inserting () or creating a tuple) to match the receiver.
"-Ypartial-unification", // Enable partial unification in type constructor inference
"-Ywarn-dead-code", // Warn when dead code is identified.
"-Ywarn-extra-implicit", // Warn when more than one implicit parameter section is defined.
"-Ywarn-inaccessible", // Warn about inaccessible types in method signatures.
"-Ywarn-infer-any", // Warn when a type argument is inferred to be `Any`.
"-Ywarn-nullary-override", // Warn when non-nullary `def f()' overrides nullary `def f'.
"-Ywarn-nullary-unit", // Warn when nullary methods return Unit.
"-Ywarn-numeric-widen", // Warn when numerics are widened.
"-Ywarn-unused:implicits", // Warn if an implicit parameter is unused.
"-Ywarn-unused:imports", // Warn if an import selector is not referenced.
"-Ywarn-unused:locals", // Warn if a local definition is unused.
"-Ywarn-unused:params", // Warn if a value parameter is unused.
"-Ywarn-unused:patvars", // Warn if a variable bound in a pattern is unused.
"-Ywarn-unused:privates", // Warn if a private member is unused.
"-Ywarn-value-discard" // Warn when non-Unit expression results are unused.
)
}
EOF
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