[Haskell-beginners] cabal: updating a package

[Andres Löh]

Hi.

> Hi there! Excuse me, but I am a bit bewildered; should I really have to give
> cabal --force-reinstalls to upgrade yesod to the new version 1.1.0.2? It
> says a lot of packages are likely to be broken, as per the paste
> http://pastebin.com/cYdZkShu.

I strongly suggest not to use --upgrade-dependencies. It's probably
unavoidable to break *some* (Yesod-related) packages for a framework
with as many dependencies as Yesod has, unless you use sandboxing. But
you shouldn't go ahead installing something if packages like
"bin-package-db" or "ghc" appear among the ones that are going to be
broken. I've just tested that starting from the 2012.2.0.0 platform
and yesod-platform-1.0.4.2, a simple

$ cabal install --dry-run yesod

yields

Resolving dependencies...
In order, the following would be installed:
clientsession-0.8.0 (new version)
conduit-0.5.2.3 (new version)
attoparsec-conduit-0.5.0 (new version)
blaze-builder-conduit-0.5.0 (new version)
http-types-0.7.3 (new version)
network-conduit-0.5.0 (new version)
shakespeare-1.0.1.1 (new version)
hamlet-1.1.0.2 (new version)
shakespeare-css-1.0.1.4 (new version)
shakespeare-i18n-1.0.0.2 (reinstall) changes: shakespeare-1.0.0.2 -> 1.0.1.1
shakespeare-js-1.0.0.5 (new version)
shakespeare-text-1.0.0.4 (new version)
simple-sendfile-0.2.6 (new version)
stringsearch-0.3.6.3 (new package)
tar-0.4.0.0 (new package)
unix-time-0.1.2 (new package)
fast-logger-0.2.2 (new version)
monad-logger-0.2.0 (new package)
persistent-1.0.0 (new version)
persistent-template-1.0.0 (new version)
wai-1.3.0 (new version)
wai-logger-0.2.0 (new version)
warp-1.3.0.1 (new version)
xml-types-0.3.3 (new version)
xml-conduit-1.0.3 (new version)
yaml-0.8.0.1 (new version)
yesod-routes-1.1.0 (new version)
zlib-conduit-0.5.0 (new version)
http-conduit-1.6.0 (new version)
authenticate-1.3.1 (new version)
wai-extra-1.3.0 (new version)
yesod-core-1.1.1 (new version)
yesod-json-1.1.0 (new version)
yesod-persistent-1.1.0 (new version)
yesod-form-1.1.1 (new version)
yesod-auth-1.1.1 (new version)
yesod-1.1.0.2 (new version)
Warning: The following packages are likely to be broken by the reinstalls:
yesod-platform-1.0.4.2
yesod-core-1.0.1.2
yesod-static-1.0.0.3
yesod-persistent-1.0.0.1
yesod-form-1.0.0.4
yesod-auth-1.0.2.1
yesod-1.0.1.6
yesod-json-1.0.0.1
yesod-default-1.0.1.1
Use --force-reinstalls if you want to install anyway.

for me, which looks reasonably safe to do with --force-reinstalls.

Cheers,
  Andres