Comment by DarkSucker

The article's `expression problem matrix` section states that the goal is make it `easy to add ops` and `easy to add types`. My learning of Rust so far indicates Rust satisfies both: traits satisfies the `ops` problem for all traits you want to support the op, and Rust's implementations (impl) solves the problem of adding types. Of course, for each new {op,type} combination, one must write the code, but Rust allows you to do that with its trait and generic systems. Am I missing something important?