In (path ChecksumIterator) Iter() you see something which is hard to explain verbally. Essentially, it provides a generator façade for what is underneath the surface a bucket being filled by four threads ("goroutines") concurrently. Unless things have changed markedly, it would be very difficult in Python to create a generator which produces its values with the help of some number of threads.

This is actually very easy in Python -- use a Queue[1], spawn some threads to populate it, and read from it in a generator.

Go seems interesting, but many/most of its praised features are already done better in other languages. For example, while it supports "thousands of goroutines" (green threads), Haskell supports millions of green threads[2]. Even Stackless, which is not known for performance, has faster gthreads[3].

Go also perpetuates several mistakes from C (ugly brace-delimited syntax) while dropping the true genuinely useful features (pointer arithmetic, manual memory management). Considering the wealth of high-quality, high-performance languages with mature library and compiler support (Haskell, Erlang, Factor, OCaml, even Ada), I'm mystified as to why Google would invest the time and energy into promoting yet another C clone.

I suppose in a year, Go will be another mostly-abandoned language with a few users poking around the mailing list asking "what happened?". Most News.YC readers can name at least one language released to great fanfare, but with little developer adoption.

[1] http://docs.python.org/library/queue.html

[2] http://www.reddit.com/r/programming/comments/a4n7s/stackless...

[3] http://dalkescientific.com/writings/diary/archive/2009/11/15...