Question

I am trying to install my Yesod web app on another machine.

I have it installed fine on my current machine and can cabal install it on there without any problems.

I seem to run into trouble with it on the other machine though (which is a fresh Ubuntu VM – e.g., no cabal packages where installed on it prior.

Note that I changed nothing about my setup (e.g. cabal files are exactly the same).

This is the error I keep getting:

cabal: cannot configure zlib-enum-0.2.2. It requires zlib-bindings ==0.1.*
For the dependency on zlib-bindings ==0.1.* there are these packages:
zlib-bindings-0.1.0 and zlib-bindings-0.1.0.1. However none of them are available.
zlib-bindings-0.1.0 was excluded because zlib-conduit-0.2.0.1 requires zlib-bindings >=0.0.3 && <0.1
zlib-bindings-0.1.0 was excluded because zlib-bindings-0.0.3.2 was selected instead
zlib-bindings-0.1.0 was excluded because of the top level dependency zlib-bindings ==0.0.3.2
zlib-bindings-0.1.0.1 was excluded because zlib-conduit-0.2.0.1 requires zlib-bindings >=0.0.3 && <0.1
zlib-bindings-0.1.0.1 was excluded because zlib-bindings-0.0.3.2 was selected instead
zlib-bindings-0.1.0.1 was excluded because of the top level dependency zlib-bindings ==0.0.3.2

I have tried all kind of ways to resolve this, but keep running into this same problem, no matter what path I take.

My guess is, that theses packages’ versions are conflicting at this point.

How can I resolve this until it gets fixed?

Answer 1

This is a prime example of cabal dependency hell. Theoretically, the fault lies with zlib-enum, since it should have had a major version bump to reflect the major version bump with zlib-bindings. But really, the problem is cabal’s dependency analyzer. The new one will hopefully be ready soon.

In the meanwhile, depending on zlib-enum <= 0.2.1 should work.

Also, @ehird’s answer should be helpful too, though it may not entirely solve the problem.