[Haskell-cafe] Patter matching beginner question

Hi all, I assume the following behavior has a trivial explanation. When I write: case name of "a" -> ... "b" -> ... everything works fine. But when I extract a and b to constants: c_a = "a" :: String c_b = "b" :: String case name of c_a -> ... c_b -> ... I get Patterns match(es) are overlapped. Adam