This is the home page of the project Kepler, an ongoing effort towards bringing compile-time metaprogramming to Scala. Our flavor of macros is reminiscent of Lisp macros, adapted to incorporate type safety and rich syntax. Unlike infamous C/C++ preprocessor macros, Scala macros: 1) are written in full-fledged Scala, 2) work with expression trees, not with raw strings, 3) cannot change syntax of Scala.
Macros are functions that are called by the compiler during compilation. Within these functions the programmer has access to compiler APIs. For example, it is possible to generate, analyze and typecheck code. You can learn more about macros from documentation.
Macros are now officially a part of the Scala language.
Since 2.10.0 Scala includes macros that can be enabled
with import language.experimental.macros on per-file basis
or with -language:experimental.macros on per-compilation basis.
Macros significantly simplify code analysis and code generation, which makes them a tool of choice for a multitude of real-world use cases. Scenarios that traditionally involve writing and maintaining boilerplate can be addressed with macros in concise and maintainable way. Therefore we believe that macros are a valuable asset to Scala programming language.