How to add Dependency in Scala?

Scala, a strong language that unites both object-oriented and functional programming techniques has to depend on external libraries to enhance its capabilities. To develop projects seamlessly, there must be efficient handling of these libraries. This is where dependency management becomes important. In this article, we will see the process of adding Scala dependencies with examples and step-by-step procedures.

Setting Up the Environment

To work with Scala, you need to set up your development environment. Ensure you have Scala installed and a build tool like SBT (Scala Build Tool).

1. Create a New Project Using SBT

sbt new scala/scala-seed.g8

Inside your project directory, there is a build.sbt file. This file will contain your project's configuration, including dependencies.

2. Define Your Project in build.sbt

Open build.sbt and define your project settings.

Example:

name := "MyScalaProject",
version := "0.1",
scalaVersion := "2.13.6",

3. Add Dependencies

Dependencies are added under the libraryDependencies setting.

For example, to add the popular JSON library play-json, your build.sbt might look like this:

lazy val root = (project in file("."))
.settings(
name := "MyScalaProject",
version := "0.1",
scalaVersion := "2.13.6",
libraryDependencies += munit % Test,
libraryDependencies += "com.typesafe.play" %% "play-json" % "2.9.2"
)

4. Fetch and Use Dependencies

Once you have defined your dependencies, you need to fetch them.

Run the following command in your project directory:

sbt update

5. Run Your Project

Run the following command in your project directory:

sbt run

Example 1: Adding Akka HTTP

1. Adding Akka HTTP Dependencies

libraryDependencies += "com.typesafe.akka" %% "akka-http" % "10.2.7",
libraryDependencies += "com.typesafe.akka" %% "akka-actor-typed" % "2.6.19",
libraryDependencies += "com.typesafe.akka" %% "akka-stream" % "2.6.19"

2. Complete build.sbt

import Dependencies._

ThisBuild / scalaVersion := "2.13.12"
ThisBuild / version := "0.1.0-SNAPSHOT"
ThisBuild / organization := "com.example"
ThisBuild / organizationName := "example"

lazy val root = (project in file("."))
.settings(
name := "MyScalaProject",
version := "0.1",
scalaVersion := "2.13.9",
libraryDependencies += munit % Test,
libraryDependencies += "com.typesafe.akka" %% "akka-http" % "10.2.7",
libraryDependencies += "com.typesafe.akka" %% "akka-actor-typed" % "2.6.19",
libraryDependencies += "com.typesafe.akka" %% "akka-stream" % "2.6.19"
)

3. Implementation Code

import akka.actor.ActorSystem
import akka.http.scaladsl.Http
import akka.http.scaladsl.server.Directives._

object Example1 extends App {
  implicit val system = ActorSystem("my-system")
  implicit val executionContext = system.dispatcher

  val route = path("hello") {
    get {
      complete("Hello, Akka HTTP!")
    }
  }

  Http().newServerAt("localhost", 8080).bind(route)
}

Output:

Example #2 Adding ScalaTest

1. Adding ScalaTest Dependencies

libraryDependencies += "org.scalatest" %% "scalatest" % "3.2.16" % Test

2. Complete build.sbt

import Dependencies._

ThisBuild / scalaVersion := "2.13.12"
ThisBuild / version := "0.1.0-SNAPSHOT"
ThisBuild / organization := "com.example"
ThisBuild / organizationName := "example"

lazy val root = (project in file("."))
.settings(
name := "MyScalaProject",
version := "0.1",
scalaVersion := "2.13.9",
libraryDependencies += munit % Test,
libraryDependencies += "org.scalatest" %% "scalatest" % "3.2.16" % Test
)

3. Test Implementation Code

package example

import org.scalatest.flatspec.AnyFlatSpec
import org.scalatest.matchers.should.Matchers

class Test2 extends AnyFlatSpec with Matchers {
  "A String" should "have the correct length" in {
    "Scala".length shouldEqual 5
  }
}

Output:

Example #3 Adding scala-csv Library

1. Adding scala-csv Dependencies

libraryDependencies += "com.github.tototoshi" %% "scala-csv" % "1.3.10"

2. Complete build.sbt

import Dependencies._

ThisBuild / scalaVersion := "2.13.12"
ThisBuild / version := "0.1.0-SNAPSHOT"
ThisBuild / organization := "com.example"
ThisBuild / organizationName := "example"

lazy val root = (project in file("."))
.settings(
name := "CsvWork",
libraryDependencies += munit % Test,
libraryDependencies += "com.github.tototoshi" %% "scala-csv" % "1.3.10"
)

3. Implementation Code

import scala.io.Source

object Example3 {
  def main(args: Array[String]): Unit = {
    val filename = "data.csv"
    val delimiter = ","
    val file = Source.fromFile(filename)
    for (line <- file.getLines()) {
        val fields = line.split(delimiter).map(_.trim)
        println(fields.mkString(", "))
    }
    file.close()
  }
}

Output:

Conclusion

It is easy to add dependencies in Scala particularly if you are working with sbt. By defining dependencies in the build.sbt file, you can easily manage and use external libraries, enhancing your project's capabilities and efficiency. You should be confident with adding and utilizing these kinds of stuffs into your scala jobs using the examples provided.

abulhax

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Article Tags :

• Scala