I got the following error. I am not sure how to fix the problem. Could anybody let me know what I should do? Thanks. ~$ cabal install --reinstall --force-reinstall asn1-types Resolving dependencies... Warning: The following packages are likely to be broken by the reinstalls: crypto-pubkey-types-0.4.3 asn1-encoding-0.9.0 Continuing even though the plan contains dangerous reinstalls. Downloading asn1-types-0.3.0... Configuring asn1-types-0.3.0... Building asn1-types-0.3.0... Failed to install asn1-types-0.3.0 Build log ( /Users/py/.cabal/logs/asn1-types-0.3.0.log ): Configuring asn1-types-0.3.0... Building asn1-types-0.3.0... Preprocessing library asn1-types-0.3.0... Data/ASN1/Types.hs:23:8: Could not find module ‘Data.Hourglass’ There are files missing in the ‘hourglass-0.2.9’ package, try running 'ghc-pkg check'. Use -v to see a list of the files searched for. cabal: Error: some packages failed to install: asn1-types-0.3.0 failed during the building phase. The exception was: ExitFailure 1 -- Regards, Peng