Cabal and simultaneous installations of the same package

Daniel Trstenjak daniel.trstenjak at
Mon May 11 11:04:52 UTC 2015

Hi Simon,

> It is tantalising to me that something so critical has been so long delayed.
> It’d be fantastic if it was done this summer.

I'm just wondering what kind of negative side effects it might have.

Sure, it will - most likely - make installing of cabal packages a lot
easier, especially for all non expert Haskell users.

But if multiple versions of the same library can be linked into one
binary, then the binary sizes will increase and therefore the memory
usage might increase and even performance might decrease a bit if
the number of cache misses increase.

It's certainly annoying to keep up with library updates, but in a way it
also pushes everyone forward to update their code bases, so if everything
just "works" - respectively is easy buildable - then this force might
be quite reduced.

I'm just thinking e.g. of a case where you want to use at least a
certain version of a library, because you know of major performance/bug
fixes in this version, but now a considerable part of your code base
might use an older version of this library, because the dependencies
of your project haven't been updated.


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