David Whiting created CRUNCH-651:
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Summary: (WIP) Kotlin API for Crunch
Key: CRUNCH-651
URL: https://issues.apache.org/jira/browse/CRUNCH-651
Project: Crunch
Issue Type: Improvement
Reporter: David Whiting
Assignee: David Whiting
Priority: Minor
Fix For: 1.0.0
Attachments: 0001-WIP-Kotlin-API-for-Crunch.patch
Motivation: Kotlin has recently gained a lot of popularity and people are
really starting to talk about it and see its merits; and language-wise it
should be perfect for writing data-transformation code as it has better support
for functional programming and useful type stuff than Java, without the
performance overhead and implicit mysteries of Scala.
Attached is a patch for a proof-of-concept Kotlin API for Crunch. It makes
heavy use of inlined functions so that the compiled bytecode ends up looking a
lot like standard Crunch code (I ran it through a decompiler), and should be
just as performant.
It also uses reified type parameters to construct PTypes automatically from
TypeReferences, so in most cases it's not necessary to provide a PType for
transformations.
See the example job and unit tests to get a quick idea of what kind of thing is
possible.
I've decided to share an unfinished patch with you all so that I can get some
feedback if we think this is a useful addition to the Crunch project at all,
and whether the general approach seems sensible.
Still left TODO (if we decide to finish this and add it):
* PGroupedTable API
* Extensible PType inference (I'm thinking something like
register<MyType>(pTypeForMyType))
* Support for data classes via kotlin-reflect
* Fill in any other gaps (mapWithContext, counters, ... ?)
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