Unboxing using Specialisation

In performance-critical parts of functional programs substantial performance improvements can be achieved by using unboxed, instead of boxed, data types. Unfortunately, polymorphic functions and data types cannot directly manipulate unboxed values, precisely because they do not conform to the standard boxed representation. Instead, specialised, monomorphic versions of these functions and data types, which manipulate the unboxed values, have to be created. This can be a very tiresome and error prone business, since specialising one function often requires the functions and data types it uses to be specialised as well. In this paper we show how to automate these tiresome consequential changes, leaving the programmer to concentrate on where to introduce unboxed data types in the first place.