How to create a type bounded within a certain range

Question

I would like to create a new integral type which is bounded to a certain range. I have tried:

data PitchClass = PC Int deriving (Ord, Eq, Show)

instance Bou         


        

Answer 1

Yes, not exporting the data constructor from the module is the way to go.

Instead, you export a function which does the checking as you said. This is often called a smart constructor.