Well, my extension of Wouter's datatypes proved to be unweildy....
So, I'm trying to use
http://fmapfixreturn.wordpress.com/2008/05/03/simple-extensible-records-now-quick-generic-tricks-pt-1/
for extensible records.
I ran across my first problem rather quickly!
data Expr f = In (f (Expr f))
Ok, but to make it part of a record, it needs to implement Data:
data Expr f = In (f (Expr f)) deriving Data
but this gives
No instances for (Data (f (Expr f)), Typeable (Expr f))
arising from the 'deriving' clause of a data type declaration
at Planning/Wouter.hs:77:0-42
Any hints?
Thanks,
-Ron
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
