[Haskell-cafe] pipes Producer combination

Hello, I would like to combine Producers in order to create a Producer of another type whcih combine these values I want a Producer of the 'A' type data A :: A a b by I have a Producer of 'a' values and another on of 'b' values. what is the best way to create from thoses two producers a Producer of 'A' ? Is ther a Generic way to automatically generate these combine Producers. In my programmes, I will have plenty of these combine Producers. thanks for considering. Cheers Frederic