Object-Oriented Pickler Combinators and an Extensible Generation Framework

Serialization or pickling, i.e., persisting runtime objects by converting them into a binary or text representation is ubiquitous in distributed programming. Pickler combinators are a popular approach from functional programming designed to alleviate some of the tedium of writing pickling code by hand, but they don’t translate well to object-oriented programming due to qualities like open class hierarchies and subtyping polymorphism. Furthermore, both functional pickler combinators and Java-based serialization frameworks tend to be tied to a specific pickle format, leaving programmers no choice of how their data is persisted. In this paper, we present object-oriented pickler combinators and a framework for generating them at compile-time, designed to be the default serialization mechanism of the Scala programming language. Our framework is extensible; (1) using Scala’s implicit parameters, users can add their own easilyswappable pickle format, (2) using the type class pattern, users can provide their own custom picklers to override the default behavior of the Scala pickling framework. In addition to extensibility and need for little to no boilerplate, the static generation of our OO picklers achieves a factor 6 speedup over Java Serialization, and performs on par or up to 3 times faster than popular “fast” Java serialization frameworks like Kryo.