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Known issues related to Cabal

None, we have cabal-helper now. Woo :)

Known issues related to Stack

It's not working

Make sure the dist/setup-config file doesn't exist in your project directory (the directory also containing your *.cabal file). When this file exists ghc-mod assumes you want to use cabal-install instead of Stack.

readPackageDb: inappropriate type

ghc-mod: $HOME/.stack/snapshots/x86_64-linux/lts-2.22/7.8.4/pkgdb/package.cache: GHC.PackageDb.readPackageDb: inappropriate type (not a ghc-pkg db file, wrong file magic number)

Your Stack resolver uses a different GHC version from what ghc-mod was linked with, in this case:

$ ghc-mod --version
ghc-mod version 5.3.0.0 compiled by GHC 7.10.2

VS.

$ stack ghc -- --version
The Glorious Glasgow Haskell Compilation System, version 7.8.4

cannot satisfy -package-id ... is unusable due to missing or recursive dependencies

ghc-mod: <command line>: cannot satisfy -package-id aeson-0.10.0.0-a37a650f6e5d5ca2347967c8f8609dfd: 
    aeson-0.10.0.0-a37a650f6e5d5ca2347967c8f8609dfd is unusable due to missing or recursive dependencies:
      attoparsec-0.13.0.1-9f9155916734a226d3befd6aaf235548 base-4.8.2.0-0d6d1084fbc041e1cded9228e80e264d <...>
    (use -v for more information)

Same root cause as above: readPackageDb: inappropriate type.

cabal-helper-wrapper: ghc: [...]: does not exist

Full error message:

cabal-helper-wrapper: ghc: readCreateProcess: runInteractiveProcess: exec: does not exist (No such file or directory) 

cabal-helper needs a working ghc executable at runtime to build it's wrapper component, when using only Stack's builtin GHC there is no ghc on $PATH hence this error.

To fix this simply add one of the paths in the output of the following command to your $PATH environment variable.

printf '%s\n' ~/.stack/programs/*/ghc-*/bin/

See https://github.com/kazu-yamamoto/ghc-mod/issues/660