[Haskell-cafe] Re: Patterns overlapped?
frr149 at easyjob.net
Sun Jan 13 14:05:07 EST 2008
> 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) = ...
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