GS Collections Kata w/ JCF Solutions

[Joe Bowbeer]

So far (b73), I haven't found any uses for -XDuseGraphInference.  Most of
the times I've tried it, it has thrown an AssertionException.


On Wed, Jan 16, 2013 at 6:14 PM, Raab, Donald <Donald.Raab at gs.com> wrote:

> Tried.  No luck.
>
> What is it possible for this to infer beyond normal levels of inference?
>
> > -----Original Message-----
> > From: Brian Goetz [mailto:brian.goetz at oracle.com]
> > Sent: Wednesday, January 16, 2013 8:55 PM
> > To: Raab, Donald [Tech]
> > Cc: 'Joe Bowbeer'; 'lambda-libs-spec-experts at openjdk.java.net'; Weir,
> John
> > [Tech]; Motlin, Craig P. [Tech]
> > Subject: Re: GS Collections Kata w/ JCF Solutions
> >
> > Try compiling with -XDuseGraphInference.
> >
> > On Jan 16, 2013, at 4:15 PM, Raab, Donald wrote:
> >
> > > Great suggestion.  I just gave it a try.  Max takes a comparator and
> returns
> > Optional so you have to add a call to get().  I was able to change the
> example
> > to the following:
> > >
> > > Map<Double, Collection<Customer>> multimap =
> this.company.getCustomers()
> > >    .stream()
> > >    .collect(Collectors.<Customer, Double>groupBy((Customer customer) ->
> > >        customer.getOrders()
> > >            .stream()
> > >            .explode((Stream.Downstream<LineItem> downstream, Order
> order) ->
> > {
> > >                downstream.send(order.getLineItems());
> > >            })
> > >            .map(LineItem::getValue)
> > >            .max(Comparators.naturalOrder())
> > >            .get()));
> > >
> > > I get an unchecked error on Comparators.naturalOrder() in IntelliJ, but
> > adding <Double> there makes it ugly.
> > >
> > > This is the GS Collections version of the kata, which also used max(),
> but
> > calls this method on a DoubleIterable:
> > >
> > > MutableListMultimap<Double, Customer> multimap =
> this.company.getCustomers()
> > >    .groupBy(customer -> customer.getOrders()
> > >        .asLazy()
> > >        .flatCollect(Order::getLineItems)
> > >        .collectDouble(LineItem::getValue)
> > >        .max());
> > >
> > > Unfortunately, the type inference seems to be very successful at
> thwarting
> > me trying to simplify the above example using the stream library
> features.  I
> > would like to simplify down to this but can't seem to get it to work:
> > >
> > > Map<Double, Collection<Customer>> multimap =
> this.company.getCustomers()
> > >    .stream()
> > >    .collect(groupBy((customer) ->
> > >        customer.getOrders()
> > >            .stream()
> > >            .explode((downstream, order) -> {
> > >                downstream.send(order.getLineItems());
> > >            })
> > >            .map(LineItem::getValue)
> > >            .max(Comparators.naturalOrder())
> > >            .get()));
> > >
> > >
> > > From: Joe Bowbeer [mailto:joe.bowbeer at gmail.com]
> > > Sent: Wednesday, January 16, 2013 4:21 PM
> > > To: Raab, Donald [Tech]
> > > Cc: lambda-libs-spec-experts at openjdk.java.net; Motlin, Craig P.
> [Tech];
> > Weir, John [Tech]
> > > Subject: Re: GS Collections Kata w/ JCF Solutions
> > >
> > > Thanks.
> > >
> > >
> > > Would it be better to rewrite the following using Stream.max()?
> > >
> > >
> > > .reduce(0.0, (x, y) -> Math.max(x, y))
> > >
> > > --Joe
> > >
> > >
>
>
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