Re: [Haskell] pattern matching on record fields and position

You might want to look at the 'get', 'set' and 'update' rules that DrIFT can derive. i made them to addres a lot of the same issues you mentioned. I personally think it is a travesty that data Foo = Foo { a :: Int, b :: Char } | Bar { a :: Int } let x = Bar { a = 4 } y = x { b = 'x'} results in bottom rather than just leaving x unchanged. well, travesty is too strong. but it bugs the heck out of me. but yeah, the DrIFT code derives functions that pull out fields but returns them in a possibly failing monad so you can properly handle a data type with no appropriate field. John -- John Meacham - ⑆repetae.net⑆john⑈