[Haskell-cafe] definition of data

[Adrian Neumann]

You need some type constructor:

data Tree a = Leaf a | Branch (Tree a) (Tree a)

Am 01.01.2009 um 08:32 schrieb Max.cs:

> hi all, I want to define a data type Tree a that can either be  a   
> or Branch (Tree a) (Tree a)?
>
> I tried
>
> data Tree a = a | Branch (Tree a) (Tree a) deriving Show
>
> but it seems not accpetable in haskell ?
>
> any way I could achieve this ?
>
> Thanks
>
> max
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