[Haskell-cafe] Re: Patterns overlapped?

[Fernando Rodriguez]

Hello Fernando,

> Hi,
> 
> When I compile this code, ghc complains about some overlapped patterns
> in function depth.  What on Earth is ghc talking about? O:-)
> 
> data BinTree a = EmptyTree
> | NodeBT a (BinTree a) (BinTree a)
> deriving Show
> emptyBT = EmptyTree
> depth emptyBT = 0
> depth (NodeBT _ left right) = max (1 + depth left) (1 + depth right)

Sorry, the exact error is:
    Warning: Pattern match(es) are overlapped
	     In the definition of `depth': depth (NodeBT _ left right) = ...