On Sun, Mar 22, 2015 at 11:24 AM, Herbert Valerio Riedel
On 2015-03-22 at 11:17:21 +0100, Erik Hesselink wrote:
[...]
I do this for template-haskell, since it's not possible to reinstall but cabal would occasionally try it. I can imagine it would work well to prevent the scenario you describe with network.
Why isn't it possible to reinstall TH (unless you also need to depend on the `ghc` package)? We even explicitly allowed template-haskell to be reinstallable again in Cabal as there didn't seem any reason to forbid it anymore (it's no different than e.g. `bytestring` which is reinstallable as well):
https://github.com/haskell/cabal/commit/ffd67e5e630766906e6f4c6655c067a79f73...
This was based on my experiences from some time ago. Looking at it now, I think it was just that the dependencies for template-haskell were too loose, i.e. it allowed different major versions of base. When a new version of GHC was released and I was trying it out, it would always try to install the older version, and this never worked. Now that you fixed these constraints (thanks!) it seems you can reinstall, as long as it's the same (major) version. It still prints this ominous warning even in a sandbox: Warning: The following packages are likely to be broken by the reinstalls: ghc-7.8.3 But everything seems to be fine when passing --force. So I guess I can remove the constraint... Erik