The article has some fairly reasonable rules of thumb to follow. For whatever reason I rarely find refs or agents to be useful, and lexical scoping is more limi

The article has some fairly reasonable rules of thumb to follow. For whatever reason I rarely find refs or agents to be useful, and lexical scoping is more limited and predictable than dynamic scoping. That said, I feel it's a little too harsh in places. Metadata is fine so long as you don't expect it to persist to derived data structures. If you think of metadata as being about a particular piece of data and nothing else, then you won't run into problems. One place I find metadata particularly useful is annotating event data, which could allow, for example, treating events from different sources with different priorities. I find that there are a lot of specialised tools in Clojure. Most of the time it's good advice to avoid them, but in the rare cases where they are needed, you're glad to have them. Keyword inheritance, for instance, is something I've been using recently, yet I've rarely had need of it before.