[Haskell-cafe] Re: Crypto-API is stabilizing

[Heinrich Apfelmus]

Thomas DuBuisson wrote:
>>> class (Binary p, Serialize p) => AsymCipher p where
>>>    generateKeypair :: RandomGen g => g -> BitLength -> Maybe ((p,p),g)
>>>    encryptAsym     :: p -> B.ByteString -> B.ByteString
>>>    decryptAsym     :: p -> B.ByteString -> B.ByteString
>>>    asymKeyLength       :: p -> BitLength

Is it actually necessary to use a type class here? The situation is very 
similar to

    Luke Palmer. Haskell Antipattern: Existential Typeclass.
    http://lukepalmer.wordpress.com/2010/01/24/

I suggest to use good old data types

    data Key = Key {
                 encrypt   :: B.ByteString -> B.ByteString,
                 decrypt   :: B.ByteString -> B.ByteString,
                 keyLength :: BitLength,
                 serialize :: B.ByteString}

    rsa :: RandomGen g => BitLength -> g -> ((Key,Key), g)


Regards,
Heinrich Apfelmus

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