Re: how to exploit existentials

[Jose Emilio Labra Gayo]

> There is a paper by Koen Claessen about "Type Classes and Existential 
> Types" which describes this trick and has a first part very readable. At 
> thimoment, I have not the reference, but I can try to look for it, if you 
> want.

Sorry, the author was K. Laufer and the reference is:
"Type Classes with Existential Types". Journal of Functional Programming 
(JFP), May 1996

Jose E. Labra Gayo
http://lsi.uniovi.es/~labra