Fixed Data.Avro.Schema.extractBindings.

[TikhonJelvis]

The old implementation had some odd bugs with nested type definitions, including missing types defined inside arrays and maps. This PR has a new implementation of extractBindings that fixes all the problems as well as a test case which covers a bunch of edge cases for extracting types from a schema.

[TikhonJelvis]

This addresses #61.

[TikhonJelvis]

Assuming this implementation is actually correct—I believe it is—I recommend back-porting this to older versions of the package with bug fix releases (ie 0.3.5.2, 0.3.4.3 and so on).

[AlexeyRaga]

Thanks!
The extractBindings functionality is fairly new. Do think it is a problem if we don't create bugfix releases, and instead assume that people can upgrade to the newest version?

[TikhonJelvis]

It's not ideal. There have been some breaking changes recently, so upgrading isn't entirely trivial—I know it would require some extra updates/refactoring on one of my projects at work, for example. At the same time, the fix is pretty self-contained, so back-porting it should be straightforward.

[AlexeyRaga]

OK, I'll try to find time to do it this weekend.

[AlexeyRaga]

I looked at versions 0.3.4.x and 0.3.5.x and have found that extractBindings isn't a part of these versions. It has been first introduced in 0.3.6.0 so perhaps retro-fix isn't needed for previous versions.

[TikhonJelvis]

@AlexeyRaga sorry, I didn't explain the full context here.

extractBindings was only extracted to a top-level function recently, but before that the same logic was part of buildTypeEnvironment. The older implementations of buildTypeEnvironment still have the same bug, at least with types defined inside maps. The retro fix may or may not define a top-level extractBindings, but it should fix the bug with buildTypeEnvironment.

By the way, I'm happy to write the code for fixing 0.3.4.x and 0.3.5.x, but I'm not sure how to organize it on GitHub. What can I open a PR against?

[AlexeyRaga]

@TikhonJelvis I have created branches release-0.3.4, release-0.3.5 and release-0.3.6

If you make PRs into these branches then we'll be able to release patched versions for 0.3.4 and 0.3.5

[TikhonJelvis]

@AlexeyRaga Awesome, thanks! I opened PRs against release-0.3.4 and release-0.3.5. The release-0.3.6 branch already has the correct behavior.