GS Collections Kata w/ JCF Solutions

[Raab, Donald]

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
> >
> >