Re: [Haskell-cafe] Are explicit exports and local imports desirable in a production application?

Thank you Henning. This is true. When one wishes to provide an abstract type, surely one would like to re-export the type constructor, but not the associated data constructors — so explicit exports become unavoidable. I have not accounted for this detail.

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You need explicit exports in the public interface, in my example module "A".

How so?

My example should be like so:

module A.Internal where

data T = Private Integer

module A ( T, -- do not export constructor f, ) where

import A.Internal (T(Private))

f :: FooBar f = do something with Private

You would need the export list in A for exposing T, but not Private.