[Haskell-cafe] Redundant/overlapping patterns?

Hi, Cafe, Can someone please explain this: ghci> case 1 of 2 -> 3 <interactive>:1:11: warning: [-Woverlapping-patterns] Pattern match is redundant In a case alternative: 2 -> ... *** Exception: <interactive>:1:1-16: Non-exhaustive patterns in case The non-exhaustive patterns part is obvious, but what is redundant about this match? And how can there be overlapping patterns when there's only one? Todd Wilson