User blog comment:Hyp cos/R function v2.0.1/@comment-2033667-20150409173128

Nice work. This is looking better and better.

As I noted earlier, your notation has become strongly hydralike at this point. In fact, your syntax rules prescribe a tree with the following rules: a root node with a special label, all children of the root node having label 0, and all other nodes being labeled with any nonnegative integer. Does this sound familiar? :)

For this reason I advise you to ditch the "scanning" and "+m}" rhetoric (which i find confusing and tedious) and use terminology for hydras instead.