$ cabal install ghc-mod
Resolving dependencies...
In order, the following would be installed:
cmdargs-0.10.10 (new package)
convertible-1.1.0.0 (new package)
djinn-lib-0.0.1.2 (new package)
djinn-ghc-0.0.2.2 (new package)
ghc-paths-0.1.0.9 (new package)
ghc-syb-utils-0.2.2 (new package)
hscolour-1.20.3 (new package)
io-choice-0.0.5 (new package)
nats-0.2 (reinstall) changes: hashable-1.2.2.0 -> 1.2.1.0
polyparse-1.9 (new package)
cpphs-1.18.5 (new package)
haskell-src-exts-1.16.0 (new package)
semigroups-0.15.3 (reinstall) changes: bytestring-0.10.4.0 -> 0.10.0.2,
hashable-1.2.2.0 -> 1.2.1.0, text-1.1.1.3 -> 0.11.3.1,
unordered-containers-0.2.5.0 -> 0.2.3.0
uniplate-1.6.12 (new package)
hlint-1.9.5 (new package)
void-0.6.1 (reinstall) changes: hashable-1.2.2.0 -> 1.2.1.0
contravariant-1.2 (reinstall)
comonad-4.2.2 (reinstall)
semigroupoids-4.2 (reinstall)
bifunctors-4.1.1.1 (reinstall)
profunctors-4.2.0.1 (reinstall)
free-4.9 (reinstall)
either-4.3.1 (reinstall)
monad-journal-0.4.0.2 (new package)
ghc-mod-5.1.0.2 (new package)
cabal: The following packages are likely to be broken by the reinstalls:
machines-0.2.5
machines-io-0.1.0.0
machines-directory-0.0.0.1
vector-instances-3.3
mono-traversable-0.6.2
chunked-data-0.1.0.1
keys-3.10.1
pointed-4.1
conduit-1.2.0.2
yaml-0.8.9.1
dlist-instances-0.1
Use --force-reinstalls if you want to install anyway.