tempgist.md

Code:

data Tree a = EmptyTree | Node (Tree a) a (Tree a) deriving (Show, Typeable, Data)

Error:

    • Can't make a derived instance of ‘Data (Tree a)’:
        You need DeriveDataTypeable to derive an instance for this class
    • In the data declaration for ‘Tree’

import Data.DeriveDataTypeable 

error:

    Could not find module ‘Data.DeriveDataTypeable’
    It is not a module in the current program, or in any known package.