How to reset Haskell package cache
cabal, haskell, package-management
Solution
Cabal sandboxes are frequently recommended for development but work well for trying out some package quickly. If anything goes wrong they are easily disposable and don't affect any other packages you have already installed. Here is what I would do to try out `clckwrks-cli` (BTW, if you want to just try out any package you might to choose another package with less dependencies).
$ cd /path/to/sandboxes
$ cabal get clckwrks-cli
$ cd clckwrks-cli-<version>
$ cabal sandbox init
$ cabal install --only-dependencies -j<N> # N is the number of CPU cores
At this point you can type `cabal run` to run the executable installed by the package (which it'll probably be at `./dist/build/bin/`), `cabal test` for running tests, or `cabal repl` in order to run a `ghci` session with the sandboxes packages available.
If anything goes wrong you can revert back the sandbox by typing `cabal sandbox delete` and `cabal clean`. When you are done you can safely remove the sandbox without affecting other packages.
Problem
Deciding to learn Haskell, installed ghc on OS X via Homebrew (web binaries weren't downloading at the time). All great, following along with Learn You a Haskell, but then decided to install some packages and see how things run. `cabal install clckwrks-cli` was running fine until... Public internet craps out half-way through install/build of a few projects. Now, none of those programs will reinstall and in the case of clckwrks-cli, I get the following error: ``` $ cabal install clckwrks-cli --reinstall --force-reinstalls Resolving dependencies... Failed to install cipher-aes-0.2.6 Failed to install cipher-rc4-0.1.4 Failed to install cookie-0.4.0.1 Failed to install crypto-numbers-0.2.3 Configuring happstack-hsp-7.2.4... Building happstack-hsp-7.2.4... Preprocessing library happstack-hsp-7.2.4... ghc: could not execute: hsx2hs Failed to install happstack-hsp-7.2.4 Failed to install lifted-base-0.2.2.0 Failed to install publicsuffixlist-0.1 Failed to install pwstore-purehaskell-2.1.1 Configuring reform-hsp-0.2.4... Building reform-hsp-0.2.4... Preprocessing library reform-hsp-0.2.4... ghc: could not execute: hsx2hs Failed to install reform-hsp-0.2.4 Failed to install web-plugins-0.2.5 Failed to install wl-pprint-text-1.1.0.2 Failed to install xml-types-0.3.4 cabal: Error: some packages failed to install: attoparsec-conduit-1.0.1.2 depends on lifted-base-0.2.2.0 which failed to install. authenticate-1.3.2.6 depends on xml-types-0.3.4 which failed to install. blaze-builder-conduit-1.0.0 depends on lifted-base-0.2.2.0 which failed to install. cipher-aes-0.2.6 failed while unpacking the package. The exception was: user error (data is not in tar format) cipher-rc4-0.1.4 failed while unpacking the package. The exception was: user error (data is not in tar format) clckwrks-0.21.1 depends on xml-types-0.3.4 which failed to install. clckwrks-cli-0.2.10 depends on xml-types-0.3.4 which failed to install. conduit-1.0.14 depends on lifted-base-0.2.2.0 which failed to install. cookie-0.4.0.1 failed while unpacking the package. The exception was: user error (data is not in tar format) cprng-aes-0.5.2 depends on cipher-aes-0.2.6 which failed to install. crypto-numbers-0.2.3 failed while unpacking the package. The exception was: user error (data is not in tar format) crypto-pubkey-0.2.4 depends on crypto-numbers-0.2.3 which failed to install. fb-0.14.11 depends on publicsuffixlist-0.1 which failed to install. happstack-authenticate-0.10.10 depends on xml-types-0.3.4 which failed to install. happstack-hsp-7.2.4 failed during the building phase. The exception was: ExitFailure 1 hsx-jmacro-7.3.4 depends on wl-pprint-text-1.1.0.2 which failed to install. http-conduit-1.9.6 depends on publicsuffixlist-0.1 which failed to install. jmacro-0.6.8 depends on wl-pprint-text-1.1.0.2 which failed to install. lifted-base-0.2.2.0 failed while unpacking the package. The exception was: user error (data is not in tar format) monad-logger-0.3.4.0 depends on lifted-base-0.2.2.0 which failed to install. publicsuffixlist-0.1 failed while unpacking the package. The exception was: user error (data is not in tar format) pwstore-purehaskell-2.1.1 failed while unpacking the package. The exception was: user error (data is not in tar format) reform-hsp-0.2.4 failed during the building phase. The exception was: ExitFailure 1 resourcet-0.4.10 depends on lifted-base-0.2.2.0 which failed to install. tls-1.1.5 depends on crypto-numbers-0.2.3 which failed to install. tls-extra-0.6.6 depends on crypto-numbers-0.2.3 which failed to install. web-plugins-0.2.5 failed while unpacking the package. The exception was: user error (data is not in tar format) wl-pprint-text-1.1.0.2 failed while unpacking the package. The exception was: user error (data is not in tar format) xml-conduit-1.1.0.9 depends on xml-types-0.3.4 which failed to install. xml-types-0.3.4 failed while unpacking the package. The exception was: user error (data is not in tar format) zlib-conduit-1.0.0 depends on lifted-base-0.2.2.0 which failed to install. ``` Same issue with a few other projects that suffered same network outage mid-install. Loving the language so far, NOT the package management :(