Cabal-install doesn't always find the "best" install plan out of the
possibly many, many options available. You can try if you get a better
one that does not upgrade "transformers", by saying
cabal install errors --constraint="transformers installed"
Cheers,
Andres
On Fri, Jan 2, 2015 at 1:19 PM, Andrew Bernard
When attempting to install the package ‘errors’ I get the following:
$ cabal install errors Resolving dependencies... In order, the following would be installed: exceptions-0.6.1 (reinstall) changes: mtl-2.1.2 -> 2.2.1, transformers-0.3.0.0 -> 0.4.2.0 transformers-base-0.4.3 (reinstall) changes: transformers-0.3.0.0 -> 0.4.2.0 monad-control-1.0.0.1 (new version) transformers-compat-0.3.3.4 (reinstall) changes: transformers-0.3.0.0 -> 0.4.2.0 contravariant-1.2 (reinstall) changes: transformers-0.3.0.0 -> 0.4.2.0 distributive-0.4.4 (reinstall) changes: transformers-0.3.0.0 -> 0.4.2.0 comonad-4.2.2 (reinstall) changes: transformers-0.3.0.0 -> 0.4.2.0 semigroupoids-4.2 (reinstall) changes: transformers-0.3.0.0 -> 0.4.2.0 bifunctors-4.2 (reinstall) profunctors-4.3.2 (reinstall) changes: transformers-0.3.0.0 -> 0.4.2.0 free-4.10.0.1 (new version) either-4.3.2.1 (new version) errors-1.4.7 (new package) cabal: The following packages are likely to be broken by the reinstalls: temporary-1.2.0.3 ghc-mod-5.2.1.1 resourcet-1.1.2.3 yaml-0.8.9.3 stylish-haskell-0.5.11.0 persistent-sqlite-1.3.0.5 persistent-1.3.3 persistent-template-1.3.2.2 monad-logger-0.3.8 hoogle-4.2.36 conduit-extra-1.1.4.2 conduit-1.2.3 either-4.3.2 monad-journal-0.5.0.1 resource-pool-0.2.3.1 monad-control-0.3.3.0 lifted-base-0.2.3.0 io-choice-0.0.5 HTF-0.12.2.3 free-4.9 Use --force-reinstalls if you want to install anyway.
I am using the ghc platform version 7.6.3.
Is this package obsolete? Why are so many packages likely to be broken?
With Haskell, how does one know what is a proper up to date package and what is not?
Andrew
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