Merge pull request scala/scala#7159 from xuwei-k/Equiv-SAM

use SAM conversion for Equiv instances

Author: lrytz

library/src/scala/math/Equiv.scala

@@ -42,20 +42,16 @@ trait LowPriorityEquiv {
 }
 
 object Equiv extends LowPriorityEquiv {
-  def reference[T <: AnyRef]: Equiv[T] = new Equiv[T] {
-    def equiv(x: T, y: T) = x eq y
+  def reference[T <: AnyRef]: Equiv[T] = { _ eq _ }
+  def universal[T]: Equiv[T] = { _ == _ }
+  def fromComparator[T](cmp: Comparator[T]): Equiv[T] = {
+    (x, y) => cmp.compare(x, y) == 0
   }
-  def universal[T]: Equiv[T] = new Equiv[T] {
-    def equiv(x: T, y: T) = x == y
-  }
-  def fromComparator[T](cmp: Comparator[T]): Equiv[T] = new Equiv[T] {
-    def equiv(x: T, y: T) = cmp.compare(x, y) == 0
-  }
-  def fromFunction[T](cmp: (T, T) => Boolean): Equiv[T] = new Equiv[T] {
-    def equiv(x: T, y: T) = cmp(x, y)
+  def fromFunction[T](cmp: (T, T) => Boolean): Equiv[T] = {
+    (x, y) => cmp(x, y)
   }
   def by[T, S: Equiv](f: T => S): Equiv[T] =
-    fromFunction((x, y) => implicitly[Equiv[S]].equiv(f(x), f(y)))
+    ((x, y) => implicitly[Equiv[S]].equiv(f(x), f(y)))
 
   @inline def apply[T: Equiv]: Equiv[T] = implicitly[Equiv[T]]
 }