Building ZIO-Neo4J: Part 1

I’m writing a blog about Scala programming and I can continue to cover the core language as much as I want, but at some point it becomes more worthwhile for me to demonstrate Scala programming in action. In this series, the first of which, we’ll be implementing a ZIO interface to the Java Neo4J driver.

At the end, we’ll be publishing artifacts for Scala 3 and a documentation website.

The Java Neo4J Driver:

Fortunately Neo4J provides us an official Neo4J driver we can use. We’ll be implementing a connection class the end user can implement as a layer in their ZIO applications.

Of course, since it’s a Java library it doesn’t utilize and Future so we can immediately wrap any effects in a ZIO effect type.

SBT Setup:

When implementing a library we need slightly a different SBT setup. Let’s tackle it in digestible pieces.

Plugins:

We’re going to use three plugins so we’ll have to change our plugins.sbt file:

addSbtPlugin("org.scalameta" % "sbt-scalafmt"   % "2.2.1")
addSbtPlugin("com.eed3si9n"  % "sbt-buildinfo"  % "0.11.0")
addSbtPlugin("com.geirsson"  % "sbt-ci-release" % "1.5.5")

Here we have scalafmt so we can automatically format our code every time we compile the project. We also have eed3si9n’s sbt-buildinfo to automatically generate build information about our project. Finally, we have sbt-ci-release to automate Sonatype releases from GitHub Actions.

Scalafmt:

We also need to create a .scalafmt.conf file for the plugin we just added. We’re going to add the following to the file:

version=2.0.1
maxColumn = 120
align = most
continuationIndent.defnSite = 2
assumeStandardLibraryStripMargin = true
docstrings = JavaDoc
lineEndings = preserve
includeCurlyBraceInSelectChains = false
danglingParentheses = true
spaces {
  inImportCurlyBraces = true
}
optIn.annotationNewlines = true

rewrite.rules = [SortImports, RedundantBraces]

SBT Build:

First we want to establish which versions of Scala we’re using. I’ll publishing for Scala 2.13 and Scala 3.1. We can now add the following to our build.sbt file:

lazy val mainScala = "3.1.2"
lazy val allScala  = Seq(mainScala, "2.13.8")

Next we want our InThisBuild:

inThisBuild(
  List(
    organization := "com.jobgun",
    homepage := Some(url("https://github.com/jobgun/zio-neo4j")),
    licenses := List("Apache-2.0" -> url("https://www.apache.org/licenses/LICENSE-2.0")),
    useCoursier := false,
    scalaVersion := mainScala,
    crossScalaVersions := allScala,
    Test / parallelExecution := false,
    Test / fork := true,
    run / fork := true,
    pgpPublicRing := file("/tmp/public.asc"),
    pgpSecretRing := file("/tmp/secret.asc"),
    pgpPassphrase := sys.env.get("PGP_PASSWORD").map(_.toArray),
    scmInfo := Some(
      ScmInfo(url("https://github.com/jobgun/zio-neo4j/"), "scm:git:[email protected]:jobgun/zio-neo4j.git")
    ),
    developers := List(
      Developer(
        "baovitt",
        "Bradly Ovitt",
        "[email protected]",
        url("https://github.com/baovitt")
      )
    )
  )
)

It’s a lot to unpack but I think it’s fairly self explanatory what’s going on. Next we want some top-level definitions:

name := "zio-neo4j"
scalafmtOnCompile := true

enablePlugins(BuildInfoPlugin)
buildInfoKeys := Seq[BuildInfoKey](name, version, scalaVersion, sbtVersion, isSnapshot)
buildInfoPackage := "zio.neo4j"

Next we want to add our dependencies:

val zioVersion = "2.0.0"

libraryDependencies ++= Seq(
  "dev.zio"                %% "zio-test"                % zioVersion % "test",
  "dev.zio"                %% "zio-test-sbt"            % zioVersion % "test",
  "dev.zio"                %% "zio"                     % zioVersion,
  "org.neo4j.driver"       % "neo4j-java-driver"        % "5.6.0"
)

Finally, we have to add some options and aliases:

scalacOptions --= Seq("-Xlint:nullary-override")

testFrameworks += new TestFramework("zio.test.sbt.ZTestFramework")

addCommandAlias("fmt", "all scalafmtSbt scalafmt test:scalafmt")
addCommandAlias("check", "all scalafmtSbtCheck scalafmtCheck test:scalafmtCheck")

Conclusion:

I just tested it and it compiles with a hello world.

Yeah!