Question

data Mine = Firstname String
          | Lastname String
          deriving (Show, Serialize)

This does not compile and gives the error

Not in scope: type constructor or class `Serialize'

Why is this not seen as member of the Serialize class although it is member of the Show class. I thought that all members of the Show class should serialize without problems?

Answer 1

That error is saying that the Serialize typeclass is not in scope. You need to import the package that defines the typeclass in order to use it. You probably want:

import Data.Serialize

from the cereal package.