Scala-Virtualized is a branch of the Scala compiler and standard library that contains a few additions to provide even better support for embedded DSLs (we call that language virtualization).

The key features are as follows:

1. overloadable control structures (while-loops, if-then-else, pattern matching), variables, object creation, etc. Scala has always translated for-comprehensions into method calls, so that the programmer can change the meaning of a for-comprehension by implementing these methods in a certain way. We generalize this to all control flow operators, as well as to the representation of mutable variables and object creation (for now limited to struct-like datatypes, but providing precise types for field-selection).

2. extension methods: define new infix-methods on existing types (pimp-my-library with less boilerplate)

• Virtualized Scala Reference: In-depth description of each feature
• Source Location and Source Context: Linking DSL expressions back to the original source
• Tutorial: Introduction
• Tutorial: Generating SQL
• Tutorial: Generating JavaScript from embedded Scala code
• Tutorial: Compiling embedded Scala code at runtime

Tutorial source code is available here.

Releases of Scala-Virtualized are binary compatible with the corresponding regular Scala release.

Here is a sample build.sbt file for use with the Simple Build Tool (SBT):

name := "My Scala-Virtualized Project"
version := "1.0"
scalaVersion := "2.10.0"
scalaOrganization := "org.scala-lang.virtualized"

Scala-Virtualized is actively used in a couple of open source projects:

• OptiML: A DSL for machine learning developed at Stanford PPL
• Scala Integrated Query (SIQ): LINQ-style database interface in Scala
• Delite: Framework/Runtime for heterogeneous parallelism
• LMS-Core: Compiler framework for embedded DSLs

Community support is available on the regular Scala mailing lists. Posts should mention scala-virtualized in the subject line.

Using Scala-Virtualized for your project? Please let us know!