Add Tuple2K Semigroupal

[rmehri01]

Closes #3410.

I wasn't really sure where in the Tuple2kInstances this should be added so I just put it in the last one so please tell me if there is somewhere else it should go. Also, should tests be added because I had a bit of trouble doing so. Thanks!

[LukaJCB]

Actually before we merge this, can we make Tuple2KSemigroupal a superclass for Tuple2KApply?

[rmehri01]

Alright I can do that. Just another thing, does it matter which tuple2k instance abstract class this goes in because there was 0-8 so I wasn't really sure and also should this be tested?

[codecov-commenter]

Codecov Report

Merging #3502 into master will decrease coverage by 0.01%.
The diff coverage is 50.00%.

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##           master    #3502      +/-   ##
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- Coverage   91.77%   91.76%   -0.02%     
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  Files         383      383              
  Lines        8400     8401       +1     
  Branches      218      216       -2     
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  Hits         7709     7709              
- Misses        691      692       +1     

[rmehri01]

Also is that import at the top of the file import cats.Contravariant needed? Intellij says it isn't used.

[joroKr21]

Alright I can do that. Just another thing, does it matter which tuple2k instance abstract class this goes in because there was 0-8 so I wasn't really sure and also should this be tested?

This is the correct place. I'm not sure about testing, I guess you would need a type that has Semigroupal but not Applicative to test this.

[rmehri01]

Alright I can do that. Just another thing, does it matter which tuple2k instance abstract class this goes in because there was 0-8 so I wasn't really sure and also should this be tested?

This is the correct place. I'm not sure about testing, I guess you would need a type that has Semigroupal but not Applicative to test this.

Ah okay thanks for the response, yeah that makes sense. Also does it matter which tuple2k instances class this goes in because I'm not really sure why they are labelled 0-8, I thought maybe it was because they had some sort of structure.

[joroKr21]

Also does it matter which tuple2k instances class this goes in because I'm not really sure why they are labelled 0-8, I thought maybe it was because they had some sort of structure.

It matters but this is the correct place to put it. The reason they exist is implicit priority. Semigroupal should have the lowest priority (same as Functor) because it has the least constraints. There is also no overlap between Functor and Semigroupal so they can be in one place without clashing.

[rmehri01]

It matters but this is the correct place to put it. The reason they exist is implicit priority. Semigroupal should have the lowest priority (same as Functor) because it has the least constraints. There is also no overlap between Functor and Semigroupal so they can be in one place without clashing.

Ah gotcha, thank you! :)

[johnynek]

Thanks for adding this!

[LukaJCB]

Awesome, thanks!

[rmehri01]

Np, thanks for the help everyone! :)