cryptocipher install fix

cabal install cryptocipher
Resolving dependencies...
Configuring cryptocipher-0.2.3...
Preprocessing library cryptocipher-0.2.3...
Preprocessing executables for cryptocipher-0.2.3...
Building cryptocipher-0.2.3...
[1 of 8] Compiling Number.Serialize ( Number/Serialize.hs, dist/build/Number/Serialize.o )
[2 of 8] Compiling Number.Generate  ( Number/Generate.hs, dist/build/Number/Generate.o )
[3 of 8] Compiling Number.ModArithmetic ( Number/ModArithmetic.hs, dist/build/Number/ModArithmetic.o )
[4 of 8] Compiling Crypto.Cipher.DSA ( Crypto/Cipher/DSA.hs, dist/build/Crypto/Cipher/DSA.o )
[5 of 8] Compiling Crypto.Cipher.RSA ( Crypto/Cipher/RSA.hs, dist/build/Crypto/Cipher/RSA.o )

Crypto/Cipher/RSA.hs:103:35:
    No instance for (Control.Monad.Error.Class.Error Error)
      arising from a use of `>>=' at Crypto/Cipher/RSA.hs:103:35-56
    Possible fix:
      add an instance declaration for
      (Control.Monad.Error.Class.Error Error)
    In the expression: dp pk c >>= unpadPKCS1
    In the definition of `decrypt':
        decrypt pk c
                  | B.length c /= (private_sz pk) = Left MessageSizeIncorrect
                  | otherwise = dp pk c >>= unpadPKCS1
                  where
                      dp = if private_p pk /= 0 && private_q pk /= 0 then
                               dpFast
                           else
                               dpSlow
cabal: Error: some packages failed to install:
cryptocipher-0.2.3 failed during the building phase. The exception was:
ExitFailure 1

FIX: cabal install mtl