Enhancements to Haddock -> Markdown conversion

[serras]

Fixes #341

[ndmitchell]

Any chance of some tests? I could imagine future changes breaking some of the more subtle bits.

[serras]

I can try, but I've already had the problem that the documentation from packages changes from version to version. I'm planning to have a look at #7 and #270, and then we can write tests which reference files in the project itself.

[ndmitchell]

I was thinking just a pure function, so take the Show of the DocH for unsafePerformIO as it stands today, paste it in as a test, and paste the current output as a string, and confirm that the conversion takes one to the other.

[serras]

That makes sense. I'll write some of them during the weekend.

[serras]

@ndmitchell the tests are in. Let me tell you what you think. Right now I've chosen two of the "hardest" ones: Num and unsafePerformIO, since they involve lists and mixed code.

[ndmitchell]

Tests look great! Thanks for doing that.

[moodmosaic]

👍 I pulled this on my local and I can verify that this fixes #341. Thank you, @serras. 💯

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Still, adding some tests should be nice, as @ndmitchell suggested. If no similar tests are in place though, perhaps we should merge and add those separately.

[cocreature]

Thanks! Pushed a small change to make the tests a bit more readable.