Add Order->Ordering implicit conversion to implicits, instances #1670
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| object Order extends OrderFunctions[Order] { | ||
| trait OrderToOrderingConversion { | ||
| /** | ||
| * Implicitly convert a `Order[A]` to a `scala.math.Ordering[A]` |
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This is not an implicit conversion which is something else. Can we say something like "provide an Ordering instance equivalent to the Order".
It does convert, and so I know I'm being pedantic, but I really don't like implicit conversions except for method enrichment, and in any case an implicit conversion has exactly one non-implicit parameter.
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I agree, but I changed this comment already. I am not seeing how it showed up here 😛
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Ah sorry. Forgot to push. Is the edited one alright?
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| ev.toOrdering | ||
| } | ||
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| object Order extends OrderFunctions[Order] with OrderToOrderingConversion { |
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I haven't researched this, but I am wondering if we place the method directly in the object instead of a trait, will that help binary comp going forward (on scala 2.11.x)?
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Is there any benefit to having implicit final def catsKernelOrderingForOrder[A](implicit ev: Order[A]): Ordering[A] inside the Order companion object? I don't think that scala will look here when it is searching for an Ordering instance. I could see a minor benefit of having a non-implicit version of this method inside the companion object. As it stands it seems like it's just a liability as I would expect you to get ambiguous implicits if you've imported both cats.implicits._ and cats.kernel.Order._.
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Now I don't know why I thought that would be a valid point to make. It has to be a trait for cats.implicits._. Sorry about the noise.
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for those following at home, the mima check failed on kernel. |
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I know that this isn't binary compatible. Is code duplication an acceptable fix? |
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@edmundnoble code duplication is an acceptable fix (i.e. they don't need to share the trait). |
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Codecov Report
@@ Coverage Diff @@
## master #1670 +/- ##
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+ Coverage 94.17% 94.17% +<.01%
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Files 256 256
Lines 4207 4208 +1
Branches 93 93
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+ Hits 3962 3963 +1
Misses 245 245
Continue to review full report at Codecov.
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Binary compatible, now. |
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I wonder if this is going to create ambiguous implicits. Can we have a test where we do |
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Ambiguity test added; it passes, I'm fairly sure the reason is that the |
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@johnynek Any more feedback? Just rebased on master and squashed. |
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👍 |
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Merged with two sign-offs. |
Does... anyone know where I would put a test? If it's worth testing? Also, kernel is open for changes for 1.0, right?