Scrap more boilerplate: reflection, zips, and generalised casts

Writing boilerplate code is a royal pain. Generic programming promises to alleviate this pain by allowing the programmer to write a generic "recipe" for boilerplate code, and use that recipe in many places. In earlier work we introduced the "Scrap your boilerplate" approach to generic programming, which exploits Haskell's existing type-class mechanism to support generic transformations and queries. This paper completes the picture. We add a few extra "introspective" or "reflective" facilities, that together support a rich variety of serialisation and de-serialisation. We also show how to perform generic "zips", which at first appear to be somewhat tricky in our framework. Lastly, we generalise the ability to over-ride a generic function with a type-specific one. All of this can be supported in Haskell with independently-useful extensions: higher-rank types and type-safe cast. The GHC implementation of Haskell readily derives the r...

• Type: Conference
• Year: 2004
• Where: ICFP
• Authors: Ralf Lämmel, Simon L. Peyton Jones
• Keywords: Boilerplate Code, Generic Programming, Generic Transformations, ICFP 2004, Programming Languages