On Friday 22 October 2010 6:37:49 am Max Bolingbroke wrote: > This is all well and good, but it means when working with data types > defined in this manner you have to write Roll and unroll everywhere. > This is tedious :-(
Your discovery is interesting (and I haven't seen it before). Another solution, though, is SHE. With it, you can write: data ListF a r = NilF | ConsF a r newtype List a = Roll (ListF a (List a)) pattern Nil = Roll NilF pattern Cons x xs = Roll (ConsF x xs) And not worry about Rolls anymore. -- Dan http://personal.cis.strath.ac.uk/~conor/pub/she/ _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
