Add Compose instance for Map #2402
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Fix binary compatibility issues by moving the new Compose instance for Map to a separate trait.
Codecov Report
@@ Coverage Diff @@
## master #2402 +/- ##
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- Coverage 95.01% 94.88% -0.14%
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Files 349 350 +1
Lines 6000 6258 +258
Branches 222 284 +62
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+ Hits 5701 5938 +237
- Misses 299 320 +21
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| @@ -15,6 +15,8 @@ class MapSuite extends CatsSuite { | |||
| checkAll("Map[Int, Int] with Option", UnorderedTraverseTests[Map[Int, ?]].unorderedTraverse[Int, Int, Int, Option, Option]) | |||
| checkAll("UnorderedTraverse[Map[Int, ?]]", SerializableTests.serializable(UnorderedTraverse[Map[Int, ?]])) | |||
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| checkAll("Compose[Map]", ComposeTests[Map].compose[Int, Long, String, Double]) | |||
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nit, can we add the SerializableTests as the other instances here?
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Thanks @denisrosca! That was a quick turnaround and an excellent job maintaining binary compatibility.
Looking at your implementation, it looks correct. However, I feel a bit uneasy about relying solely on the ComposeLaws as tests. All they test is associativity, so I believe that a trivial implementation that always returned an empty Map would satisfy the CompseLaws. Could you please add some tests verifying that Map composition works as one would expect? I'd even be satisfied with just adding some sbt-doctest examples.
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| trait MapInstancesBinCompat0 { | ||
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| implicit def catsStdComposeForMap: Compose[Map] = new Compose[Map] { |
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Should this be a val instead of a def so the same instance can be reused repeatedly?
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@ceedubs Would a doctest like this be enough? |
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@denisrosca that example looks great! |
* Add Compose instance for Map * Move Compose instance for Map to separate trait Fix binary compatibility issues by moving the new Compose instance for Map to a separate trait. * Serialization test for Compose instance for Map * Add doctest for Compose[Map]
Closes #2399