On Sunday 08 July 2007, Andrew Coppin wrote:
Jonathan Cast wrote:
I think surely you're using existential data types rather than rank-2 types.
You expect *me* to know?
Surely not :) That's why I tried briefly explaining the ideas again.
Existential types: each application of Encoder2 is to arguments which require a specific value of x.
Rank-2 types (polymorphic fields, actually): each application of Encoder2 is to arguments which work with any value of x.
All I know is it didn't compile, so I added {-# LANGUAGE Rank2Types #-}, and now it works. *shrugs*
If you're happy, then I guess I can accept the situation. I think you'll trip over the distinction again, but that's just me. Jonathan Cast http://sourceforge.net/projects/fid-core http://sourceforge.net/projects/fid-emacs