Faster Scala Collections with Compile-Time Reflection

We describe the implementation of specific Scala collections operations (currently the map and foreach methods) using the Scala 2.10 compile-time reflection facilities. The primary motivation for this work is to create faster collections by inlining operations at the call site. The functionality is available at the standard Scala library level, so that our optimized operations can be used on all plain Scala collection types (e.g., List, Array, etc.) without the need of creating new specialized types. Our mechanism is implemented directly inside the Scala standard library and by modifying the default compiler. The results are encouraging since benchmarks show a 40% speedup. SUBJECT AREA: Compile-Time Metaprogramming