Error installing in Windows

[mcandre]

When I try to install the latest version of random-fu on Windows, Cabal reports a dependency error.

Specs:

C:\>ghc --version
The Glorious Glasgow Haskell Compilation System, version 7.0.4

C:\>cabal --version
cabal-install version 0.10.2
using version 1.10.2.0 of the Cabal library

Trace:

C:\> cabal install random-fu-0.2.1.1
Registering rvar-0.2...
Configuring random-fu-0.2.1.1...
Warning: This package indirectly depends on multiple versions of the same package. This is highly likely to cause a compile failure.
package gamma-0.9.0.2 requires template-haskell-2.5.0.0
package th-extras-0.0.0.1 requires template-haskell-2.5.0.0
package random-source-0.3.0.2 requires template-haskell-2.5.0.0
package random-fu-0.2.1.1 requires template-haskell-2.5.0.0
package flexible-defaults-0.0.0.3 requires template-haskell-2.5.0.0
Preprocessing library random-fu-0.2.1.1...
Building random-fu-0.2.1.1...
<command line>: cannot satisfy -package-id random-source-0.3.0.2-3d669417cb45bca9678de9943dbdc9fe:
    random-source-0.3.0.2-3d669417cb45bca9678de9943dbdc9fe is unusable due to missing or recursive dependencies:
      flexible-defaults-0.0.0.3-22c17f0e579a7185b4c42e3b41b44483 template-haskell-2.5.0.0-87f4f416a22a910e480ac9f269479a5f th-extras-0.0.0.1-ffc8557b5d37ebd5852a23d82de5203a
    (use -v for more information)
cabal: Error: some packages failed to install:
random-fu-0.2.1.1 failed during the building phase. The exception was:
ExitFailure 1

[mokus0]

I'm not able to reproduce this here. I'm running Vista 32-bit on VMWare, I did a fresh install of the Haskell platform (GHC 7.0.4, cabal-install 0.10.2, Cabal 1.10.2.0), ran "cabal update" and "cabal install random-fu" and it built version 0.2.1.1 successfully.

From your error messages it looks to me more like there are old broken packages in your ghc-pkg database. For example, where it says:

<command line>: cannot satisfy -package-id random-source-0.3.0.2-3d669417cb45bca9678de9943dbdc9fe:
    random-source-0.3.0.2-3d669417cb45bca9678de9943dbdc9fe is unusable due to missing or recursive dependencies:
      flexible-defaults-0.0.0.3-22c17f0e579a7185b4c42e3b41b44483 template-haskell-2.5.0.0-87f4f416a22a910e480ac9f269479a5f th-extras-0.0.0.1-ffc8557b5d37ebd5852a23d82de5203a

The fact that it's got an ABI hash at the end of the version number means it's trying to use a version already installed, but then it says it can't because it has missing dependencies (other packages that were already installed). This happens sometimes when you re-build existing packages. Different choices of dependencies, build flags, etc., cause the new version to have a different ABI hash, which breaks other installed packages that depend on the one that was rebuilt.

Incidentally, this is why it's generally considered a Bad Idea to use "cabal upgrade" - it rebuilds packages too eagerly and often leads to breakages exactly like this one.

I recommend running "ghc-pkg check" to see what installed packages are broken and using "ghc-pkg unregister" to remove them. If that still doesn't fix it, it might be helpful to send me the output of "ghc-pkg list" so I can see whether something else you have installed might be depending on something that conflicts with random-fu.

[mcandre]

On my machine, Source.DevRandom was missing, so I attempted to install random-source. That's then the problem occurred. Try cabal install random-source.

[mokus0]

random-source installed fine for me as a part of the process of installing random-fu. I also had no problem re-installing it from scratch. Would you mind posting the output of "ghc-pkg check" and "cabal install -v random-fu-0.2.1.1"?

BTW, Data.Random.Source.DevRandom will always be missing on windows because on windows there's no such thing as /dev/random. If you use the MonadRandom instance for IO, it will use /dev/random on unix systems and something else on windows (currently either the mwc package or System.Random, depending on GHC version).

[mcandre]

BTW, Data.Random.Source.DevRandom will always be missing on windows because on windows there's no such thing as /dev/random.

Ah, I thought so. Would it be a good idea to use System.Random so that my code works on both Windows and Unix?

[mokus0]

All of the other sources work on both windows and unix. If you don't have a strong preference for which algorithm to use, I would recommend just using "sample" in IO.

[mokus0]

Was this issue ever resolved? If so, I'd like to close it. If not, would you mind posting the output of "ghc-pkg check" and "cabal install -v random-fu-0.2.1.1"?

Thanks!