Issue installing Snap on macOS Sierra

Question

I'm having trouble installing the Haskell framework Snap on macOS Sierra. Whenever I install it, I get the following message:

Resolving dependencies...
Configuring securemem-0.1.9...
Configuring skein-1.0.9.4...
Configuring configurator-0.3.0.0...
Configuring cryptonite-0.24...
Building configurator-0.3.0.0...
Building securemem-0.1.9...
Building skein-1.0.9.4...
Failed to install configurator-0.3.0.0
Build log ( /Users/nicholas/.cabal/logs/ghc-8.2.1/configurator-0.3.0.0-6dySPcNCURWFswtMXJvzho.log ):
cabal: Entering directory '/tmp/cabal-tmp-66175/configurator-0.3.0.0'
Configuring configurator-0.3.0.0...
Preprocessing library for configurator-0.3.0.0..
Building library for configurator-0.3.0.0..
<command line>: cannot satisfy -package-id attoparsec-0.13.2.0-5dp4kBDsiGY4dQpLKbD5rk: 
    attoparsec-0.13.2.0-5dp4kBDsiGY4dQpLKbD5rk is unusable due to shadowed dependencies:
      scientific-0.3.5.1-L0qYzdp0wpz8rO8gircNSR text-1.2.2.2-EGUst8sqNAZCw1xLPcmcMH
    (use -v for more information)
cabal: Leaving directory '/tmp/cabal-tmp-66175/configurator-0.3.0.0'
Configuring transformers-base-0.4.4...
Building cryptonite-0.24...
Building transformers-base-0.4.4...
Installed securemem-0.1.9
Installed transformers-base-0.4.4
Installed skein-1.0.9.4
Installed cryptonite-0.24
Updating documentation index
/Users/nicholas/Library/Haskell/share/doc/x86_64-osx-ghc-8.2.1/index.html
cabal: Error: some packages failed to install:
configurator-0.3.0.0-6dySPcNCURWFswtMXJvzho failed during the building phase.
The exception was:
ExitFailure 1
snap-1.0.0.2-5CZKyA9EY4oLgkpHYCVfnv depends on snap-1.0.0.2 which failed to
install.

I'm using the Haskell Platform installed using homebrew (brew cask install haskell-platform), and cabal version 2.0.0.2. I have tried using sudo and deleting my ~/.ghc file

Answer 1

This looks like a bug in Cabal 2 (or potentially GHC 8.2). See https://github.com/haskell/cabal/issues/4728. I'd recommend sticking to GHC 8.0.2 for the moment with either cabal 1.24 or Stack. I'm the case of Stack, the version won't matter, since it will use the Cabal version shipped with GHC.

Answer 2

There was an issue with full 8.2.1 binary platform builds that's just been resolved: https://mail.haskell.org/pipermail/haskell-cafe/2017-October/127979.html

This was likely an instance of that.

(see also: GHC cannot find libraries on fresh install of Haskell-Platform)