Re: [Haskell-cafe] Again, version conflicting problem with cabal-install

I think this could be gone with cabal-dev only if A has a new version or the compiled one that could use C-0.2 or caba-dev could ignore the version constraint. So it is kind of an "old binary" problem. It could also be resolved by reinstall A to use C-0.2 with cabal-install. The problem I met is that, A uses B and C-0.2, and B uses C-0.1. Both dependencies to C were strict. I had not gotten any B or C installed. Now I just started to install A. It would fail. In fact, there was a chance that I just modified B.cabal to use C-0.2 and all things done. But there also was a risk of unable to compile or even runtime crash. I am just wanting an option (ignore versions) to take that risk in develop environment. 2012/2/3 Jason Dagit :

In my experience the diamond of death is typically because:  * You install package A that uses C-0.1  * Someone uploads C-0.2 to hackage  * Later you 'cabal update', this does not rebuild A to use C-0.2, even though it could.  * You install package B that uses C, and cabal builds it with C-0.2  * Now you want to build D that uses A and B, but A requires C-0.1 and B requires C-0.2, even though they could be rebuilt to use the same C.

Typically, the constraints on A, B, and D would all accept the same version of C.  Except that when they were compiled separately and C changed between building A and B, then the compiled versions become fixed on C-0.1 and C-0.2.

It's true that it won't solve it in all cases, but in my experience using cabal-dev made the problem go away.

I hope that clarifies.

Jason

On Fri, Feb 3, 2012 at 7:33 AM, Magicloud Magiclouds wrote:

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Well, cabal-dev could not resolve the conflict of "the diamond". Because the conflict is "depending different version at the SAME time".

On Fri, Feb 3, 2012 at 9:20 PM, Jason Dagit wrote:

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On Thu, Feb 2, 2012 at 9:54 PM, Magicloud Magiclouds wrote:

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Hello,  As I recalled, ghc works in staticly link mode. So after one library is compiled, all its build dependencies are useless. Lost, changed, wheresoever, it does not matter.  Then why the problem of version conflicting exists?

I'm not sure, but for me this problem has gone away by using cabal-dev to build everything.

Jason

-- 竹密岂妨流水过 山高哪阻野云飞

And for G+, please use magiclouds#gmail.com.

-- 竹密岂妨流水过 山高哪阻野云飞 And for G+, please use magiclouds#gmail.com.