Scala performance question

Question

In the article written by Daniel Korzekwa, he said that the performance of following code:

list.map(e => e*2).filter(e => e>10)

is muc

Answer 1

The solution lies mostly with JVM. Though Scala has a workaround in the figure of @specialization, that increases the size of any specialized class hugely, and only solves half the problem -- the other half being the creation of temporary objects.

The JVM actually does a good job optimizing a lot of it, or the performance would be even more terrible, but Java does not require the optimizations that Scala does, so JVM does not provide them. I expect that to change to some extent with the introduction of SAM not-real-closures in Java.

But, in the end, it comes down to balancing the needs. The same while loop that Java and Scala do so much faster than Scala's function equivalent can be done faster yet in C. Yet, despite what the microbenchmarks tell us, people use Java.