Attempting to build the haddocks for the gh-pages branch, but I'm getting something I've never seen before.
Macintosh:free ekmett$ cabal haddock
Running Haddock for free-4.6...
Preprocessing library free-4.6...
Warning: The documentation for the following packages are not installed. No
links will be generated to these packages: bifunctors-4.1.1, comonad-4.0,
contravariant-0.4.4, distributive-0.4, hashable-1.2.1.0, mtl-2.1.2,
nats-0.1.2, profunctors-4.0.2, semigroupoids-4.0, semigroups-0.12.2,
tagged-0.7, text-1.1.0.1, transformers-compat-0.1.1.1,
unordered-containers-0.2.3.3
<no location info>:
module ‘free-4.6:Main’ is defined in multiple files: dist/build/tmp-92156/src/Control/Applicative/Free.hs
dist/build/tmp-92156/src/Control/Alternative/Free.hs
dist/build/tmp-92156/src/Control/Comonad/Cofree.hs
dist/build/tmp-92156/src/Control/Comonad/Cofree/Class.hs
dist/build/tmp-92156/src/Control/Comonad/Trans/Cofree.hs
dist/build/tmp-92156/src/Control/Comonad/Trans/Coiter.hs
dist/build/tmp-92156/src/Control/Monad/Free.hs
dist/build/tmp-92156/src/Control/Monad/Free/Church.hs
dist/build/tmp-92156/src/Control/Monad/Free/Class.hs
dist/build/tmp-92156/src/Control/Monad/Free/TH.hs
dist/build/tmp-92156/src/Control/Monad/Trans/Free.hs
dist/build/tmp-92156/src/Control/Monad/Trans/Free/Church.hs
dist/build/tmp-92156/src/Control/Monad/Trans/Iter.hs
dist/build/tmp-92156/src/Control/MonadPlus/Free.hs