Breaking change in patch level release

[sol]

I just realized that the semantics of splitDirectories changed between system-filepath-0.4.13.1 and system-filepath-0.4.13.2.

ghci> splitDirectories "foo/bar/baz"
Loading package system-filepath-0.4.13 ... linking ... done.
[FilePath "foo",FilePath "bar",FilePath "baz"]

ghci> splitDirectories "foo/bar/baz"
Loading package system-filepath-0.4.13.2 ... linking ... done.
[FilePath "foo/",FilePath "bar/",FilePath "baz"]

WTF!

[sol]

718ba6f

[sol]

Not sure what to do about this, but patch level is not even detectable with CPP...

[snoyberg]

That change was intended to be a bug fix, and only correct incorrect behavior. Can you give me an example of this change causing breakage?

[sol]

Consider e.g.

isBoring :: FilePath -> Bool
isBoring p = ".git/" `elem` dirs || "dist/" `elem` dirs
  where
    dirs = splitDirectories p

vs

isBoring :: FilePath -> Bool
isBoring p = ".git" `elem` dirs || "dist" `elem` dirs
  where
    dirs = splitDirectories p

The first works for system-filepath-0.4.13.2 and newer, the second worked with earlier versions, but will not work as expected with system-filepath-0.4.13.2 and newer.

[snoyberg]

Thanks, that's a good counterexample. It looks like our best bet is to revert the change and release a new patch release, would you concur?

[sol]

0.4.13.2 has been out for a couple of months already. I have no picture on how much code depends on the new behavior and how much code depends on the old one.

If we stick with the current behavior we should probably deprecate all versions < 0.4.13.2, if we revert the change we should deprecated 0.4.13.2 and 0.4.13.3.

BTW, is there some discussion that motivated this change?

[snoyberg]

Issue #3 covers this.

There are unfortunately a lot of problems in the library around how it handles issues of this nature. Someone from the FP Complete team will be putting up a public issue and/or blog post about some proposed changes soon, which will hopefully address them all by simplifying the library.

[sol]

I'm fine with either way.

Personally, I just refrain from changing code at all in patch level releases, not even bug fixes, for the simple reason that you can't CPP on patch level.

For the specific case of splitDirectories it's of course valid to challenge current semantics and change it. But this is a breaking change that will effect user code.

In https://github.com/hspec/autospec I currently rely on the system-filepath-0.4.13.2 semantics and I added a lower bound, so I'm covered.

[sol]

Going forward, an other option would be to deprecate 0.4.13.2 and 0.4.13.3 and release current master as 0.5.0.

[snoyberg]

Note that I've just announced that these libraries will be deprecated in favor of filepath and directory: https://plus.google.com/+MichaelSnoyman/posts/Ft5hnPqpgEx

[sol]

I think that's the right call.

Sent from my iPhone

On 12 May 2015, at 3:42 pm, Michael Snoyman [email protected] wrote:

Note that I've just announced that these libraries will be deprecated in favor of filepath and directory: https://plus.google.com/+MichaelSnoyman/posts/Ft5hnPqpgEx

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