I've put together a small package for lazifying record types. There's a "classy" version in Data.Lazify and a Generic-only version in Data.Lazify.Generic. A few examples are below. I'd love to hear comments on what looks good and what should be changed before I make the first release. As usual, names are the hardest part. Note especially that the operator ($~) is defined in *both* Data.Lazify and Data.Lazify.Generic, and that no operator corresponds to genericLazify. Hrmm mumble.

lazify (1, 2) = (1, 2)

lazify undefined = (_|_, _|_, _|_)

lazify undefined = Sum (_|_, _|_, _|_)

genericLazify (1,2) = (1,2)

genericLazify undefined = (_|_, _|_, _|_)

genericLazify (Sum (MyCon x y)) = ... oops, MyType isn't an instance of Lazifiable

lazifyGeneric (1,2) = (1,2)

lazifyGeneric undefined = (_|_, _|_, _|_)

lazifyGeneric (Sum (MyCon x y)) = Sum (MyCon x y)

Thanks in advance,

David