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Hash[Map[K, V]] has unnecessary constraint #3039 #3060

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Hash[Map[K, V]] has unnecessary constraint #3039 #3060

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c5e5e37
Hash[Map[K, V]] has unnecessary constraint #3039
vasiliybondarenko Sep 13, 2019
88e221a
fix binary compatibility
larsrh Oct 5, 2019
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6 changes: 3 additions & 3 deletions core/src/main/scala/cats/instances/sortedSet.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -73,7 +73,7 @@ trait SortedSetInstances extends SortedSetInstances1 {
private[instances] trait SortedSetInstances1 {
@deprecated("2.0.0-RC2", "Use cats.kernel.instances.sortedSet.catsKernelStdHashForSortedSet")
private[instances] def catsKernelStdHashForSortedSet[A: Order: Hash]: Hash[SortedSet[A]] =
cats.kernel.instances.sortedSet.catsKernelStdHashForSortedSet[A]
cats.kernel.instances.sortedSet.catsKernelStdHashForSortedSet1[A]

@deprecated("2.0.0-RC2", "Use cats.kernel.instances.sortedSet.catsKernelStdSemilatticeForSortedSet")
def catsKernelStdSemilatticeForSortedSet[A: Order]: BoundedSemilattice[SortedSet[A]] =
Expand All @@ -94,7 +94,7 @@ private[instances] trait SortedSetInstancesBinCompat0 {
private[instances] trait SortedSetInstancesBinCompat1 extends LowPrioritySortedSetInstancesBinCompat1 {
// TODO: Remove when this is no longer necessary for binary compatibility.
implicit override def catsKernelStdHashForSortedSet[A: Order: Hash]: Hash[SortedSet[A]] =
cats.kernel.instances.sortedSet.catsKernelStdHashForSortedSet[A]
cats.kernel.instances.sortedSet.catsKernelStdHashForSortedSet1[A]
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@travisbrown
Just noticed this, should this method be deprecated and un-implicit like the one above? The Todo comment should probably be removed too?

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@kailuowang What's happening here is tricky: these instances were in the wrong place (cats.instances.SortedSetInstances1 instead of cats.kernel.instances), and now that they're in the right place these bincompat traits get the methods from both, which results in an inherits conflicting members compiler error, which means we have to bubble overrides all the way to the top.

}

private[instances] trait LowPrioritySortedSetInstancesBinCompat1
Expand All @@ -104,7 +104,7 @@ private[instances] trait LowPrioritySortedSetInstancesBinCompat1
cats.kernel.instances.sortedSet.catsKernelStdOrderForSortedSet[A]

override def catsKernelStdHashForSortedSet[A: Order: Hash]: Hash[SortedSet[A]] =
cats.kernel.instances.sortedSet.catsKernelStdHashForSortedSet[A]
cats.kernel.instances.sortedSet.catsKernelStdHashForSortedSet1[A]
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@travisbrown, not sure what this override is for? Can we add a comment?

}

@deprecated("2.0.0-RC2", "Use cats.kernel.instances.SortedSetHash")
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15 changes: 11 additions & 4 deletions kernel/src/main/scala/cats/kernel/instances/SortedSetInstances.scala
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@@ -1,11 +1,14 @@
package cats.kernel
package instances

import cats.kernel.{BoundedSemilattice, Hash, Order}
import scala.collection.immutable.SortedSet

trait SortedSetInstances extends SortedSetInstances1 {
implicit def catsKernelStdHashForSortedSet[A: Order: Hash]: Hash[SortedSet[A]] =
@deprecated("Will be removed after dropping Scala 2.11 support", "")
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Can the deprecated message be "Use catsKernelStdHashForSortedSet1 instead", "2.1.0" ?

def catsKernelStdHashForSortedSet[A: Order: Hash]: Hash[SortedSet[A]] =
new SortedSetHash[A]

implicit def catsKernelStdHashForSortedSet1[A: Hash]: Hash[SortedSet[A]] =
new SortedSetHash[A]
}

Expand All @@ -28,9 +31,13 @@ class SortedSetOrder[A: Order] extends Order[SortedSet[A]] {
StaticMethods.iteratorEq(s1.iterator, s2.iterator)
}

class SortedSetHash[A: Order: Hash] extends Hash[SortedSet[A]] {
// FIXME use context bound in 3.x
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Just curious, context bound breaks BC here (even with the deprecated constructor)?

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Yes, because it affects the constructor.

class SortedSetHash[A](implicit hashA: Hash[A]) extends Hash[SortedSet[A]] {
import scala.util.hashing.MurmurHash3._

@deprecated("Use the constructor _without_ Order instead, since Order is not required", "2.0.1")
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Nit: more likely that the derrecate version is 2.1.0

def this(o: Order[A], h: Hash[A]) = this()(h)

// adapted from [[scala.util.hashing.MurmurHash3]],
// but modified standard `Any#hashCode` to `ev.hash`.
def hash(xs: SortedSet[A]): Int = {
Expand All @@ -50,7 +57,7 @@ class SortedSetHash[A: Order: Hash] extends Hash[SortedSet[A]] {
finalizeHash(h, n)
}
override def eqv(s1: SortedSet[A], s2: SortedSet[A]): Boolean =
StaticMethods.iteratorEq(s1.iterator, s2.iterator)(Order[A])
StaticMethods.iteratorEq(s1.iterator, s2.iterator)(Eq[A])
}

class SortedSetSemilattice[A: Order] extends BoundedSemilattice[SortedSet[A]] {
Expand Down