DrIFT...
...once known as Derive

I've not got the time to actively maintain DrIFT at the moment. Happily, Malcolm Wallace has produced an updated implementation for Haskell 98. He writes

Other changes include the addition of a rule for deriving the "Binary"
class (available as a library for both nhc98 and ghc), and altering
Main.main to write its results to stdout instead of overwriting the
original file.

So far, I have only tested this version of DrIFT with nhc98 - I do not
have the latest version of ghc available.  Hence, it will probably
require a little bit of tweaking to be made completely portable.
The sources are here:
   
ftp://ftp.cs.york.ac.uk/pub/haskell/contrib/DrIFT-1.0-98.tar.gz

Introduction

DrIFT is a type sensitive preprocessor for Haskell. It extracts type declarations and directives from modules. The directives cause rules to be fired on the parsed type declarations, generating new code which is then appended to the bottom of the input file. The rules are expressed as Haskell code, and it is intended that the user can add new rules as required.

DrIFT is written in Haskell 1.4, can be compliled using GHC 2.2 or higher, or interpreted using Hugs 1.4

So, what does DrIFTdo?

DrIFT automates instance derivation for classes that aren't supported by the standard compilers. In addition, instances can be produced in seperate modules to that containing the type declaration. This allows instances to be derived for a type after the original module has been compiled. As a bonus, simple utility functions can also be produced from a type.

Features

DrIFT comes with a set of rules to produce instances for all derivable classes given in the Hasekell Prelude. There's a rule to produce instances of NFData (the orignal motivation of all this), and rules for utility functions on types also.
DrIFT performs import chasing to find the definition of a type.
In addition to literate and non-literate scripts, DrIFT is able to extract information from interface files generated by the GHC compiler
Code is generated using pretty-printing combinators. This means that the output is (fairly) well formatted, and easy on the eye.
Effort has been made to make the rule interface as easy to use as possible. This is to allow users to add rules to generate code specific to their own projects. As the rules are themselves written in Haskell, the user doesn't have to learn a new language to express rules.

Browse the DrIFT Manual

DrIFT Distribution

DrIFT for Hugs / Runhugs 1.4
DrIFT for GHC 2.02 upwards
Documentation (dvi) (html) (info)
DrIFT Emacs mode, written by Hans W. Loidl

I'd like to hear comments, criticism, or praise? from anybody using DrIFT . I'd be especially interested in any new rules written for it. Feel free to suggest improvements or bug fixes too.

Progress

For some time I've been meaning to go back to the source code, rewriting & debugging sections of it. I've still not gotten round to doing this, but plan to do so before Christmas 1998. Improvements planned include :

Support for multi-parameter type classes & other features of the new type checker
Bugfixes.The current distribution has a few problems:

somtimes it chokes on literate scripts
Import chasing fails occasionally
know of any more? get in touch

Possibly change the command syntax -- use standard `deriving clauses', use as a pre-processor for Hugs
Add a better installation mechanism

nww@dcs.gla.ac.uk