GitHub user cloud-fan opened a pull request:
https://github.com/apache/spark/pull/4131
[CORE][minor]remove unnecessary use of existential type in DAGScheduler
In `DAGScheduler` we use `(TaskContext, Iterator[_]) => _` to represent the
type of the function that process the elements of RDD. And it's a shorthand for
`(TaskContext, Iterator[T] forSome {type T}) => U forSome {type U}`, means we
don't care what's the type parameter of Iterator and the return type of this
function.
As `Iterator` and the return type of `Function2` is covariant,
`(TaskContext, Iterator[_]) => _` is actually identical to `(TaskContext,
Iterator[Any]) => Any`.
So I think we can avoid using existential type here and make the code clear
and simple.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/cloud-fan/spark minor
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/4131.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #4131
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commit 42af1db00ae827f89c140d9f4274ab60620d76b1
Author: Wenchen Fan <[email protected]>
Date: 2015-01-21T04:39:51Z
remove unnecessary use of existential type in DAGScheduler
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