T3592.hs:8:5:
    No instance for (Show (T a)) arising from a use of `show'
    In the expression: show
    In an equation for `f': f = show

T3592.hs:11:7:
    No instance for (Show a) arising from a use of `show'
    Possible fix:
      add (Show a) to the context of
        the type signature for g :: T a -> String
    In the expression: show x
    In an equation for `g': g x = show x