Add (.:!) and partially revert d0414be92ee6bf5b4c057978955b89d111767dab

[phadej]

Handle #83 by introducing .:! as @gregwebs proposed (I bikeshedded .:?? to .:!). Fixes undocumented breaking change in 0.10

Related: #287

[dmjio]

+1

[gregwebs]

great, this needs to be merged. only problem is that we have a bunch of operators with slightly different semantics. A big improvement would be to give a non-operator name to all of them. And better yet would be to make combinators to describe how maybe is treated.

undefinedAsNull "maybeField"

[phadej]

Probably shouldn't be part of this PR, but I'd like to have names too.

How about

parseField = (.:)
parseOptionalField = (.:?)
parseNotNullOptionalField = (.:!) -- this one is huge :(
withDefault = (.!=)

[gregwebs]

Can we get this released now as version 0.11 to avoid breaking everyone with 0.10 ?

[k-bx]

@phadej this needs to be rebased

[phadej]

Rebased (and fixed the build sdist): https://travis-ci.org/phadej/aeson/builds/85721736

Please, setup travis for all of us!

[nikomi]

+1!

This was almost 2 months ago - is anything happening with this?

[bos]

Applied, thanks.

[gregwebs]

@phadej does it make sense to apply this now that 0.10 has been released or is this a breaking change back in the other direction?

[phadej]

@gregwebs, if the next release is 0.11...

[gregwebs]

But what is the point of making a 0.11 release that makes things like 0.9 if 0.10 is out? Isn't this merge 3 months late?

[phadej]

I cannot really comment on that, as I'm author and user of aeson-compat which makes (.:?) in 0.10 behave like it was in 0.9. IMO 0.9 behaviour is more useful, your mileage may vary.

[gregwebs]

This is obviously better and it would have been great to be merged before the 0.10 release. However, many people changed their code to work with 0.10. Those that did not take a compatible approach will just need to change it back to 0.9 behavior now.

[tolysz]

I am just testing if this PR actually fixes my Maybe ~ Null case; otherwise my patch makes aeson behave correctly (i.e. pre 10 )

[codygman]

Should this close #287?

[wereHamster]

@gregwebs there are also many people who haven't upgraded their package yet (due to this and other problems with the 0.10 release), for them keeping the 0.9 semantics would be preferable.

[nikomi]

+1

I assumed the null-handling API change to be an unintended glitch that would be corrected in the next version, probably marking 0.10.0.0 as deprecated.