Scala Macros

Scala Macros are a metaprogramming feature in the Scala programming language that allows developers to write code that generates or transforms other code at compile-time. They enable compile-time code generation, static analysis, and domain-specific language (DSL) creation by manipulating abstract syntax trees (ASTs). This powerful tool helps reduce boilerplate, enforce invariants, and optimize performance by shifting work from runtime to compile-time.

Also known as: Scala Macro, Scala Metaprogramming, Scala Compile-time Macros, Scala AST Macros, Scala Def Macros

Why learn Scala Macros?

Developers should learn Scala Macros when building libraries or frameworks that require compile-time code generation, such as serialization libraries (e.g., for JSON or XML), type-safe database query builders, or performance-critical applications where runtime overhead must be minimized. They are particularly useful in Scala projects for creating expressive DSLs, automating repetitive code patterns, and performing advanced static checks that go beyond standard type system capabilities.

Learning Resources

• docs: Scala Macros Guide
• tutorial: Scala Macros Tutorial by Li Haoyi
• video: Metaprogramming in Scala 2 and 3
• course: Scala Macros: The Big Picture
• book: Programming in Scala, 5th Edition (Chapter on Macros)