| A possibly related question is whether you would expect to make record | selectors and updaters work for all record types at the same time? | That would definitely be very useful.
I'm not sure what you mean by this. Would you care to elaborate?
The most important thing for me is supporting record update for existentially quantified data records, as in the error below. In general I also find working with code that involves existential type variables quite hard work - for example I can't use foo as a record selector either, even if I immediately do something that seals the existential type back up again. I don't understand this stuff well enough to be sure whether it's an impredicativity issue or not, though. Cheers, Ganesh Foo.hs:11:8: Record update for the non-Haskell-98 data type `Foo' is not (yet) supported Use pattern-matching instead In the expression: rec {foo = id} In the definition of `f': f rec = rec {foo = id} {-# LANGUAGE Rank2Types #-} module Foo where data Foo = forall a . Foo { foo :: a -> a, bar :: Int } x :: Foo x = Foo { foo = id, bar = 3 } f :: Foo -> Foo f rec = rec { foo = id } g :: Foo -> Foo g rec = rec { bar = 3 } ============================================================================== Please access the attached hyperlink for an important electronic communications disclaimer: http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html ==============================================================================