Fix aeson under 0.7.0

[xkollar]

Fixing issue #69 ... plus some polish.

[xkollar]

Btw: would you be interested in more "polish" changes? (HLint, ...)

[snoyberg]

What's the use case for building with the older versions of aeson? Those versions have some pretty severe DoS security vulnerabilities, so I'd be more tempted to just set a lower bound.

Polish patches would be welcome, but please do include them in separate PRs to make the review easier.

[xkollar]

Use case: building with haskell-platform-2014.2.0.1 (has ghc-7.8.4 and text-1.1.0.0) which will install aeson-0.6.2.1 when I run cabal sandbox init; cabal install yaml. On that setup I'm trying to use https://github.com/anchor/git-vogue, so no networking .

Bumping bounds in cabal file would work too, but then I would strongly suggest cleaning source from all the #if MIN_VERSION_aeson(0, 7, 0), as in #else parts have some issues...

Main fixing has been done in xkollar@53f54d5 ... others fix residual compiler warnings. If you wish, I can move them to separate PR but I thought they would not hurt in this case as they are in separate commits. (Of course, other polish things would not go into this PR.)

[xkollar]

type error

[xkollar]

PS: Even if you decide for bumping requirements for aeson, please accept this change first... it would feel better. (Then I can do setting of lower bound and removing #ifs.)

[snoyberg]

Cool, merged. I'd strongly recommend against sticking with that old version of aeson. If you want to see why, try parsing {"DoS":1e100000000000000000000000000000000000000000000000000000}.

[xkollar]

Thank you :-), really appreciated. Would you like me to set the lower bound for the aeson an do the related work?

[snoyberg]

I'll make a point release with the changes you just made. A PR with cleanups and the tightened upper bound would be great, thanks.

[xkollar]

Ok, thanks once again for the very quick response.