In Haskell, why non-exhaustive patterns are not compile-time errors?
This is a follow-up of http://stackoverflow.com/questions/3799359/why-am-i-getting-non-exhaustive-patterns-in-function-when-i-invoke-my-haskel I understand that using -Wall, GHC can warn against non-exhaustive patterns. I'm wondering what's the reason behind not making it a compile-time error by default given that it's always possible ...