Hello Lennart, Monday, March 6, 2006, 9:50:24 AM, you wrote: LA> Yes, I've read the article too. And I really like the record system. LA> But an off-hand remark like that doesn't convince me. my own opinion is that this scheme is like classes - they can be resolved at compile time in most real cases but noone do it because code will be too large. if some function can accept any records which has field 'a' then to use this function on records of different types we need either to do specialization or use scheme with non-constant access time also, while i like dynamic records for some types of tasks, i think that the "spirit" of Haskell in whole is to give explicit definitions of all types used and in this respect this type extension in not on "main way". i will be glad to write smth like this: data A = A { f1 :: Integer -- filesize , f2 :: String -- filename } data B : A = B { f3 : Int -- filedate , f4 : Int -- filetime } i.e. explcicitly define concrete types as a set of fields, explicitly define types of fields and make comments just here. in this respect, O'Haskell is what i really like -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com