In his last post, Antonio Cangiano gives his personal definition of evangelism:
Bringing to the attention of other programmers innovations that I find, which can make us more productive or help us produce better software. It's a matter of awareness, there is no intention of pushing anything on anyone.
He explains that finding interesting innovations requires to explore new languages and frameworks and that passion for learning is the only motivation.
Now that Ruby has no secret for him, Antonio Cangiano lists the main criteria for selecting a new language to learn. He argues that only functional languages could meet the new concurrency requirements introduced by multiple core/processor architectures. In passing, he points out that Ruby green threading model cannot leverage such architectures.
If we have 2,4 or 16 cores, we better start thinking about how to develop applications that take full advantage of them. Concurrent and parallel programming can be quite tedious and error prone when adopting languages that are not designed for these requirements. Ruby's current lack of native threads is then particularly unfortunate in these scenarios, as it implies that Ruby will take advantage of a single processor only.
Keeping only Erlang and Haskell on his short list, Antonio Cangiano explains his personal choice for Haskell as a new personal challenge and concludes with a "How to get started with Haskell" section.