I'm not sure why cabal has decided that it's best to reinstall a new version of transformers, that seems very strange to me. You can probably work around this by running:<br><div><br></div><div> cabal install errors --constraint 'transformers == 0.3.0.0'</div><div><br></div><div>I *would* recommend upgrading to GHC 7.8, as a number of packages have stopped supporting 7.6.3. (For the record, I don't believe any of the packages you have installed have dropped backwards compatibility.) And generally, I recommend using Stackage to avoid these kinds of versioning problems. There are instructions at:</div><div><br></div><div> <a href="http://www.stackage.org">http://www.stackage.org</a></div><div><br></div><div>Fair warning: I'm the primary Stackage maintainer.</div><br><div class="gmail_quote">On Fri Jan 02 2015 at 2:19:20 PM Andrew Bernard <<a href="mailto:andrew.bernard@gmail.com">andrew.bernard@gmail.com</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div style="font-family:Lucida Sans Unicode,Arial;font-size:15px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto">When attempting to install the package ‘errors’ I get the following:</div><div style="font-family:Lucida Sans Unicode,Arial;font-size:15px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto"><br></div><div style="font-family:Lucida Sans Unicode,Arial;font-size:15px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto"><div style="margin:0px">$ cabal install errors</div><div style="margin:0px">Resolving dependencies...</div><div style="margin:0px">In order, the following would be installed:</div><div style="margin:0px">exceptions-0.6.1 (reinstall) changes: mtl-2.1.2 -> 2.2.1, transformers-0.3.0.0</div><div style="margin:0px">-> 0.4.2.0</div><div style="margin:0px">transformers-base-0.4.3 (reinstall) changes: transformers-0.3.0.0 -> 0.4.2.0</div><div style="margin:0px">monad-control-1.0.0.1 (new version)</div><div style="margin:0px">transformers-compat-0.3.3.4 (reinstall) changes: transformers-0.3.0.0 -></div><div style="margin:0px">0.4.2.0</div><div style="margin:0px">contravariant-1.2 (reinstall) changes: transformers-0.3.0.0 -> 0.4.2.0</div><div style="margin:0px">distributive-0.4.4 (reinstall) changes: transformers-0.3.0.0 -> 0.4.2.0</div><div style="margin:0px">comonad-4.2.2 (reinstall) changes: transformers-0.3.0.0 -> 0.4.2.0</div><div style="margin:0px">semigroupoids-4.2 (reinstall) changes: transformers-0.3.0.0 -> 0.4.2.0</div><div style="margin:0px">bifunctors-4.2 (reinstall)</div><div style="margin:0px">profunctors-4.3.2 (reinstall) changes: transformers-0.3.0.0 -> 0.4.2.0</div><div style="margin:0px">free-4.10.0.1 (new version)</div><div style="margin:0px">either-4.3.2.1 (new version)</div><div style="margin:0px">errors-1.4.7 (new package)</div><div style="margin:0px">cabal: The following packages are likely to be broken by the reinstalls:</div><div style="margin:0px">temporary-1.2.0.3</div><div style="margin:0px">ghc-mod-5.2.1.1</div><div style="margin:0px">resourcet-1.1.2.3</div><div style="margin:0px">yaml-0.8.9.3</div><div style="margin:0px">stylish-haskell-0.5.11.0</div><div style="margin:0px">persistent-sqlite-1.3.0.5</div><div style="margin:0px">persistent-1.3.3</div><div style="margin:0px">persistent-template-1.3.2.2</div><div style="margin:0px">monad-logger-0.3.8</div><div style="margin:0px">hoogle-4.2.36</div><div style="margin:0px">conduit-extra-1.1.4.2</div><div style="margin:0px">conduit-1.2.3</div><div style="margin:0px">either-4.3.2</div><div style="margin:0px">monad-journal-0.5.0.1</div><div style="margin:0px">resource-pool-0.2.3.1</div><div style="margin:0px">monad-control-0.3.3.0</div><div style="margin:0px">lifted-base-0.2.3.0</div><div style="margin:0px">io-choice-0.0.5</div><div style="margin:0px">HTF-0.12.2.3</div><div style="margin:0px">free-4.9</div><div style="margin:0px">Use --force-reinstalls if you want to install anyway.</div><div><br></div><div>I am using the ghc platform version 7.6.3.</div><div><br></div><div>Is this package obsolete? Why are so many packages likely to be broken?</div><div><br></div><div>With Haskell, how does one know what is a proper up to date package and what is not?</div><div><br></div><div>Andrew</div><div><br></div></div><div><div><div> </div></div></div><br><div></div></div>______________________________<u></u>_________________<br>
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