On Mon, 22 Apr 2002, Simon Peyton-Jones wrote:
Actually, GHC does automatically specialise for all types at which the function is called in that module, but it doesn't do it across modules. Why not? Because it compiles bottom-up, whereas the specialisation info is really top-down.
Have often thought that we could spit out specialisation info into .spec files, and have some separate program to eat up all the .spec files and produce specialisation pragmas for all the modules... but never got around to it. It would produce quite a worthwhile speedup though, if anyone feels inclined to tackle it.
(If anyone does, I have a good plan of action in my head.)
I advise anyone thinking of doing this to read: F. Bueno, M. Garcia de la Banda, M. Hermenegildo, K. Marriott, G. Puebla, and P. Stuckey. A model for inter-module analysis and optimizing compilation. In Kung-Kiu Lau, editor, Tenth International Workshop on Logic-based Program Synthesis and Transformation, LNCS 2042, pages 86--102. Springer-Verlag, July 2001. www.cs.mu.oz.au/~pjs/papers/lopstr2000.ps.gz The examples are all logic programming based, but much should be applicable to functional programs. And if that doesn't scare you off, maybe this will: Nicholas Nethercote. The Analysis Framework of HAL. Master's Thesis, University of Melbourne, September 2001. www.cl.cam.ac.uk/~njn25/pubs/masters2001.ps.gz (Chapter 7) It's more specific (describes a particular implementation) and goes into more of the gruesome details. -- Nick Nethercote njn25@cam.ac.uk