Merge pull request scala/scala#8142 from dwijnand/prefer-PartialFunction-runWith-over-isDefinedAt-and-apply

Prefer PartialFunction#runWith over isDefinedAt/apply

Author: SethTisue

library/src/scala/collection/immutable/TreeSeqMap.scala

@@ -250,10 +250,7 @@ final class TreeSeqMap[K, +V] private (
     while (iter.hasNext) {
       val k = iter.next()
       val (_, v) = mapping(k)
-      if (pf.isDefinedAt((k, v))) {
-        val (k2, v2) = pf((k, v))
-        bdr.addOne(k2, v2)
-      }
+      pf.runWith({ case (k2, v2) => bdr.addOne(k2, v2) })((k, v))
     }
     bdr.result()
   }

library/src/scala/jdk/DoubleAccumulator.scala

@@ -185,8 +185,7 @@ final class DoubleAccumulator
     val s = stepper
     while (s.hasStep) {
       val n = s.nextStep()
-      if (pf.isDefinedAt(n))
-        b.addOne(pf.apply(n))
+      pf.runWith(b.addOne)(n)
     }
     b.result()
   }

library/src/scala/jdk/IntAccumulator.scala

@@ -190,8 +190,7 @@ final class IntAccumulator
     val s = stepper
     while (s.hasStep) {
       val n = s.nextStep()
-      if (pf.isDefinedAt(n))
-        b.addOne(pf.apply(n))
+      pf.runWith(b.addOne)(n)
     }
     b.result()
   }

library/src/scala/jdk/LongAccumulator.scala

@@ -185,8 +185,7 @@ final class LongAccumulator
     val s = stepper
     while (s.hasStep) {
       val n = s.nextStep()
-      if (pf.isDefinedAt(n))
-        b.addOne(pf.apply(n))
+      pf.runWith(b.addOne)(n)
     }
     b.result()
   }