[Haskell-cafe] Error when installing RSA (for yesod) with GHC 7.2.1

[Thomas DuBuisson]

Try to install with: cabal install RSA 'random == 1.0.1.0'

I'm guessing the issue is your "random" library is less than 1.0.1 and
also includes an instance of Word8 (in other words, the GHC release
you use pulled an unofficial version from the repo).

Cheers,
Thomas

On Mon, Oct 24, 2011 at 2:13 PM, Yves Parès <limestrael at gmail.com> wrote:
> I'm using GHC 7.2.1 and cabal-install 0.8 (Cabal 1.8.0.2), and when
> "cabal install rsa"
>
> I got the error
> $ cabal install rsa
> Resolving dependencies...
> Configuring RSA-1.0.6.2...
> Preprocessing library RSA-1.0.6.2...
> Preprocessing executables for RSA-1.0.6.2...
> Building RSA-1.0.6.2...
> [1 of 1] Compiling Codec.Crypto.RSA ( Codec/Crypto/RSA.hs,
> dist/build/Codec/Crypto/RSA.o )
>
> Codec/Crypto/RSA.hs:580:10:
>     Duplicate instance declarations:
>       instance Random Word8 -- Defined at Codec/Crypto/RSA.hs:580:10-21
>       instance Random Word8 -- Defined in System.Random
> cabal: Error: some packages failed to install:
> RSA-1.0.6.2 failed during the building phase. The exception was:
> ExitFailure 1
>
> Apparently it's an instance being declared twice.
> However RSA hackage page states that it compiles under GHC 7.2:
> http://hackage.haskell.org/package/RSA
>
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