Parallel dimensions

Brian Goetz opens JAX London with ‘The Road to Lambda’

Elliot Bentley

In the opening keynote of this week’s JAX London, Java Language Architect Brian Goetz outlined the hows and whys of Java 8’s headline feature.

Taking to the stage for the opening keynote of JAX London, Java
Language Architect Brian Goetz spoke of the challenges of evolving
a language as established as Java, focusing on Java 8’s headline
feature, Lambdas.

He started by giving a mention the London Java Community, who
helped run a workshop exploring the new feature in partnership with
JAX London over the weekend, and were presented with a Duke’s
Choice award recently at JavaOne.

Proclaiming he has “the best job in the world”, Goetz then
presented a pie chart illustrating “what people think I do”,
including “being a jerk on mailing lists”, “stealing features from
other languages”, and mostly “syntax”.

On a following slide titled “what (it feels like) I actually do”,
the majority was taken up with “compatibility”, as well as “keeping
features out” (to stop it getting “out of hand”, said Goetz) and
“regretting serialisation” (“It was an awful idea 17 years ago when
it was created, and we’re still regretting it”).

Goetz noted: “The slices for adding things are really quite small,
and the slices for identifying things we shouldn’t add are really
quite big.”

Yet, that doesn’t mean there shouldn’t be any progress. “In the
eight years since Java 5, there’s been kind of a lull in the
evolution of the platform,” he said, “and we’re trying to make up
for lost time.”

When adding new features, said Goetz, there are a number of things
to consider: adapting to change and righting past wrongs, while
maintaining both compatibility and keeping the language “true to
the spirit of Java”.

Goetz then moved on to the meat of the keynote, focusing on the
introduction of closures (or, as they are know in Java, Lambdas) to
Java 8. With a history dating back to experimental “pizza” work in
1997, he admitted that “it’s been a long journey, and it’s nice to
be nearly at the end of that”.

Whilst back in 1995, when Java was first released, closures were
considered “too hard” for ordinary developers, today Java is “the
last holdout”, said Goetz, and now we are living in a “parallel
world” it no longer makes sense to use sequential logic. He noted a
key inspiration for this work was Guy Steele’s presentation “How to
think about parallel programming – not!”.

Utilising an example where a ‘for’ loop was rewritten to use a
Lambda and Collection.forEach, Goetz illustrated how “what” and
“how” could be decoupled, allowing responsibility to be moved to
the library. “It’s a small, seemingly innocuous change that changes
a lot of things,” said Goetz.

Another example was of sorting a list by surname, which today would
involve at least five lines and a Comparator. Using Lambdas, it is
now possible with just one line of code – and it also looks more
like problem statement. “We could have done this with innerClass,
but we wouldn’t have bothered,” he said.

Summing, Goetz admitted: “We’re catching up with the competition –
it’s the truth.” But he was positive that this new feature will
empower library developers while “gently pushing [Java users]
towards functional programming, without using the F word”.

He finished by stating that “there’s a lot more work to do”,
including dealing with the primitive-reference divide, adding more
parallel libraries, and support for value types and tuples, as well
as computation GPUs. Still, at least it Lambdas are very nearly

Photo by John

comments powered by Disqus