Did you consider Scala? From my POV it could fit your bill pretty well. It has tons of data structures for pretty much every usecase, and even lists the comple

Did you consider Scala? From my POV it could fit your bill pretty well. It has tons of data structures for pretty much every usecase, and even lists the complexity of various operations. All the data structures share the same API so replacing one with another is fairly painless. 2. — 8. are all no problem in Scala and running on the JVM means not having to worry about speed or stability anymore, while having all the superior tools of the JVM ecosystem for monitoring and debugging available to you. 9. Macros will ship as an experimental feature in 2.10, to make sure everything can be adjusted and fixed as necessary before declaring it stable. 10. Perl 5/6 is still ahead in Unicode, but judging from the Unicode presentation by Tom Christiansen the JVM is more or less on the second place, which fits with my experience. Overall Scala is a impressively well-designed language imho, although some people really dislike that it doesn't restrict method names like Java does.