gistfile1.txt

-- crypto-api                                                                                                                                                                                 
import qualified Crypto.Classes
-- cryptonite                                                                                                                                                                                 
import qualified Crypto.Cipher.Types

-- Implement the crypto-api BlockCipher typeclass for all cryptonite                                                                                                                          
-- BlockCipher instances.                                                                                                                                                                     
instance Crypto.Cipher.Types.BlockCipher cipher => Crypto.Classes.BlockCipher cipher where                                                                                                   
  blockSize = Crypto.Cipher.Types.blockSize (undefined :: cipher)                                                                                                                            
  encryptBlock = Crypto.Cipher.Types.ecbEncrypt                                                                                                                                              
  decryptBlock = Crypto.Cipher.Types.ecbDecrypt                                                                                                                                              

gistfile2.txt

/home/exarkun/Work/haskell/tahoe-lafs-immutable-uploader/aesctr/Main.hs:49:10: error:
    • The constraint ‘Crypto.Cipher.Types.BlockCipher cipher’
        is no smaller than
        the instance head ‘Crypto.Classes.BlockCipher cipher’
      (Use UndecidableInstances to permit this)
    • In the instance declaration for
        ‘Crypto.Classes.BlockCipher cipher’
   |
49 | instance Crypto.Cipher.Types.BlockCipher cipher => Crypto.Classes.BlockCipher cipher where
   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^