Backport unzip method in functor typeclass for scala_2.11

[gagandeepkalra]

addresses #3143

[codecov-io]

Codecov Report

Merging #3234 into scala_2.11 will increase coverage by <.01%.
The diff coverage is 100%.

@@              Coverage Diff              @@
##           scala_2.11   #3234      +/-   ##
=============================================
+ Coverage        93.5%   93.5%   +<.01%     
=============================================
  Files             382     383       +1     
  Lines            7147    7149       +2     
  Branches          194     193       -1     
=============================================
+ Hits             6683    6685       +2     
  Misses            464     464

Impacted Files	Coverage Δ
core/src/main/scala/cats/syntax/functor.scala	100% <100%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 4a7be5d...4df6869. Read the comment docs.

[gagandeepkalra]

If this looks good I can start working on other subtask for #3143

[gagandeepkalra]

I need some help with this error on running docs/makeMicrosite

[error] (docs / Jekyll / mappings) java.io.IOException: Cannot run program "jekyll" (in directory "/Users/gagandeepkalra/IdeaProjects/cats/docs/target/scala-2.11/resource_managed/main/jekyll"): error=2, No such file or directory`

Seems like it's failing for scala_2.11 branch altogether, I'm not very sure how to solve this.

[rossabaker]

Have you installed jekyll? It's a Ruby utility, and the right way to install it depends on your OS.

[gagandeepkalra]

@rossabaker thank you, now I have, and docs/makeMicrosite runs successfully on both my branch and scala_2.11. Now I wonder why is the build failing at all. I tried restarting with a dummy commit (amend) thinking it might just be flaky, but no.

build error,

[error] /home/travis/.rvm/gems/ruby-2.5.3/gems/octokit-4.14.0/lib/octokit/middleware/follow_redirects.rb:14:in `module:Middleware': uninitialized constant Faraday::Error::ClientError (NameError)
[error] Did you mean? Faraday::ClientError

ends up with.

[error] (docs / Jekyll / mappings) Could not run jekyll, error: 1

[rossabaker]

It suspect it's related to #3218. There was some recent bitrot in jekyll that broke several projects using sbt-microsites, and it doesn't look like any fix was backported to this branch.

[rossabaker]

Looks fine to me, but a more active maintainer in the 2.11 BinCompat Hell Era should look at my shrug below.

[travisbrown]

Looks fine to me, thanks.

[gagandeepkalra]

Thank you 😊