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From Victor Iacoban <victor.iaco...@gmail.com>
Subject Re: extending crunch
Date Thu, 15 Nov 2012 16:14:48 GMT
I'm not a clojure wizard myself but it feels like clojure REPL with crunch
would be a terrific experimentation environment.

I've tried crunch from java and I was impressed, it's very easy to connect
non-standard sources and reasonable easy to define the flow.

I tried to use cascalog for my prototyping env but although it's very good
on flow definition, cascading lacks a lot in flexibility when you need to
process something else except for text or sequesnce files.

"clunch" sounds like a good name to me ;)

-- victor


On Thu, Nov 15, 2012 at 10:58 AM, Joseph Adler <joseph.adler@gmail.com>wrote:

> Personally, I'd love to see Crunch mixed with Clojure. I was thinking about
> this myself, but I'd rather see someone who really knows Clojure take this
> on.
>
> Just don't call it Clunch.
>
> -- Joe
>
>
> On Thu, Nov 15, 2012 at 5:04 AM, Victor Iacoban <victor.iacoban@gmail.com
> >wrote:
>
> > Thanks Josh, will give this a try
> >
> >
> > On Wed, Nov 14, 2012 at 9:54 PM, Josh Wills <josh.wills@gmail.com>
> wrote:
> >
> > > I'm always glad to help people to extend Crunch in ways that are useful
> > for
> > > them. I think that most things that involve type-related extensions can
> > be
> > > handled using the PTypes.derived() function, which can be used to
> create
> > > custom PTypes that are mapped to underlying serialized types, so that
> you
> > > could do something like
> > >
> > > // Forgive my syntax errors, I'm doing this w/o an IDE
> > > PType<Object> objectType = PTypes.derived(Object.class, new
> > > InputMapFn<BytesWritable, Object>(), new OutputMapFn<Object,
> > > BytesWritable>(), Writables.writables(BytesWritable.class));
> > >
> > > ...which is essentially how Scrunch works: the PTypes { } functionality
> > in
> > > Scrunch maps from Scala types to Java types using the derived
> > > functionality.
> > >
> > > The Converter stuff is internal to Avro and Writable, I can't think of
> a
> > > case where that would need to be exposed outside the package (i.e.,
> once
> > > you've decided on whether to use Writables or Avro as your
> serialization
> > > framework, the choice of Converter is fixed.)
> > >
> > > If you have a use case where the derived type can't handle the
> conversion
> > > or is a poor choice for whatever reason, I'm all about having a
> > discussion
> > > and trying out different designs.
> > >
> > > Josh
> > >
> > >
> > > On Wed, Nov 14, 2012 at 6:18 PM, Victor Iacoban <
> > victor.iacoban@gmail.com
> > > >wrote:
> > >
> > > > Hi,
> > > >
> > > > I'm very interested in writing a wrapper library around Apache Crunch
> > for
> > > > Clojure, something similar to existing Scrunch.
> > > > How do you recommend to start?
> > > >
> > > > I was looking through Crunch code and it looks like I can pretty
> easily
> > > > integrate it in clojure by adding some custom WritableType type.
> > > > Something like WritableType<Object, ByteWritable> with a custom
> > converter
> > > > or inputFn/outputFn functions.
> > > >
> > > > Regretfully there are several issues with this approach and instead
> I'd
> > > > have to duplicate all those type classes for a new type set
> > > > * WritableType has a package visible constructor so I cannot extend
> it
> > > and
> > > > cannot instantiate it
> > > > * Converter is instantiated inside WritableType constructor so in
> case
> > I
> > > > need a different converter I'm stuck
> > > > * Writables has a factory method for WritableType but it's private
> > > > * it looks like there is an attempt to support additional
> WritableTypes
> > > > through EXTENSIONS in Writables but it would only work for cases
> where
> > in
> > > > WritableType<T, W> both T and W are hadoop writables
> > > >
> > > > So what do you think is a best solution, is it possible to open up
> the
> > > api
> > > > to support custom WritableTypes or the only option for me is to
> > > implement a
> > > > new ClojurePType and all related classes?
> > > >
> > > > Hope I'm not too detailed, but at this stage you all are probably
> very
> > > > familiar with the code
> > > >
> > > > Thanks,
> > > > Victor
> > > >
> > >
> >
>

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