Hello,

There are a few problems with the ghc ecosystem in guix right now (unless they have been fixed in the last month or so). The following is relevant to you.

Our version of cabal-install is incompatible with the default ghc version: http://issues.guix.gnu.org/45055

The fix for this is to use ghc@8.6.

From there you can use cabal as normal, but without the $GHC_PACKAGE_PATH variable set, i.e.:

$ env -u GHC_PACKAGE_PATH cabal new-build
I hope that helps.

Kindly,

John