[redirected to haskell-cafe] On 24 Apr 2003, Steffen Mazanek wrote:

Hello. I am sure this question is not new. Even so, please give me the solution or point me to an old thread.

How can I implement something like:

data Test = T1 Int | T2 Int test::Test->Int test (_ x) = x

Or is this impossible? In case of yes, why? This would save a lot of case differentiations in my application. Or is there an appropriate compiler option?

It can be done, but only for labeled fields. For example: data Test = T1 { test :: Int } | T2 { test :: Int } See section 3.15 of the Haskell report. Dean