S. Alexander Jacobson wrote:
Conceptually, I think what I really want is the data structure equivalent of type inference. Just as I don't want to be forced to declare my function types, I don't want to be forced to declare my data types. The field labels I use should be enough to define the shape of my type. The reason this is really important is that if hlists contain hlists, the type declarations can get really really messy
Separately, I would really like hrecords not to have order dependency. It seems strange to me that (Foo .*. Bar .*. HNil) is a different type from (Bar .*. Foo .*. HNil).
These particular two issues : type inference based on record 'shape' and records without order dependency, (ignoring the SYB part of the problem for the moment) are both addressed in the following haskell records proposal (and, undoubtedly, others) http://research.microsoft.com/~simonpj/Haskell/records.html Jules