... wherein I bloviate discursively

Brian Clapper,

SBT: A Scala-based Simple Build Tool

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Awhile ago, I embarked on an effort to build yet another build tool, this one in Scala. I shelved that effort, and I’ve switched to SBT, instead.

I’ve had it with Ant, for all the reasons outlined in my previous build tool discussion, and then some.

I looked at Maven and Ivy, but, really, I am so over XML configuration files. (Again, see previous rant.)

At one suggestion, I began to look at Gradle, a Groovy build tool with Maven, Ivy and Ant integration. Now this was looking promising: A simple code-oriented configuration (no XML! Yay!), with complete access to Ant tasks and full external dependency management.

Before diving feet-first into Gradle, though, I decided to take a closer look at SBT, a tool Daniel Spiewak recommended. SBT bills itself as “a simple build tool for Scala projects that aims to do the basics well.” SBT uses Scala, much the same way that Gradle uses Groovy; this is appealing to me, since I’m doing most of my “elective programming” in Scala these days. After digging a bit, I found that SBT has complete support for external dependency management.

  • Like Gradle, SBT has support for automatic external dependency management, using Ivy under the covers.
  • Also like Gradle, SBT integrates well with Maven repositories.
  • It’s completey trivial to support an external dependency on a jar file that isn’t in Maven.
  • If your project is laid out in a Maven directory structure (something SBT will create for you, if you want), SBT can generally figure out where everything is. If you don’t need “extras” (such as external dependencies), you don’t have to create a configuration file at all.
  • If you don’t like the Maven directory structure, or you want to change pieces of it (such as where the compiled code ends up), SBT lets you configure just those pieces easily.

In all, it’s an impressive piece of software. I switched from using Ant to using SBT to build my Grizzled Scala Library, and the resulting configuration file was 15 lines long, including blank lines and comments.

I’m building a Scala-based replacement for my Python sqlcmd tool (because I’ve come to prefer JDBC to Python’s DB API), and I switched that project over, too. The Ant build file for that project is 250 lines of XML, and it doesn’t support external dependencies. The Maven POM file (if there were one) would, of course, be smaller than that. But the configuration file for SBT is trivial, and far more readable than a pom.xml file:

import sbt._

class SQLShellProject(info: ProjectInfo) extends DefaultProject(info) {
  override def compileOptions = Unchecked :: super.compileOptions.toList

  // External dependencies

  val scalaToolsRepo = "Scala-Tools Maven Repository" at 

  val scalatest = "org.scala-tools.testing" % "scalatest" % "0.9.5"
  val joptSimple = "net.sf.jopt-simple" % "jopt-simple" % "3.1"
  val jodaTime = "joda-time" % "joda-time" % "1.6"

  // Grizzled comes from local machine for now
  val grizzled = "grizzled-scala-library" % "grizzled-scala-library" % "0.1" from 

I’m sold.