sbt

sbt is an open-source build tool for Scala and Java projects, similar to Apache's Maven and Ant.
Its main features are:

Native support for compiling Scala code and integrating with many Scala test frameworks
Continuous compilation, testing, and deployment
Incremental testing and compilation (only changed sources are re-compiled, only affected tests are re-run etc.)
Build descriptions written in Scala using a DSL
Dependency management using Apache Ivy (which supports Maven-format repositories)
Integration with the Scala interpreter for rapid iteration and debugging
Support for mixed Java/Scala projectssbt is the de facto build tool in the Scala community, used by the Lift web framework and Play Framework.
Scala's commercial outlet, Lightbend Inc., has called sbt "arguably the best tool for building Scala projects", saying that its two most prominent features are incremental compilation and an interactive shell. When continuous compilation mode is entered, the Scala compiler is instantiated only once, which eliminates subsequent startup costs, and source file changes are tracked so that only affected dependencies are recompiled. The interactive console allows modifying build settings on the fly and entering the Scala REPL along with all class files of the project. The popularity of the incremental compilation has prompted Typesafe to extract this feature in the form of an independent component called Zinc.sbt had already fed back into the Scala standard library before, when its process API was adopted in Scala 2.9.

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