"Yes, except rocketnia doesn't like coerce either."
For the record, that's true, but I do follow a coercion pattern sometimes. See the end of http://arclanguage.org/item?id=14220: "To digress a bit, coercion is a positively useful design pattern when...."
As it happens, 'each is one of those times I'd use a coercion pattern. I'd probably define these utilities, with these dependencies:
each --> some --> seqify --> entries --> keys --> unwrap-my-table
To introduce the type 'my-table and give it support for 'each, I only need to extend 'keys so that it tries 'unwrap-my-table.[1] If I do that, 'seqify will already be able to coerce my type to a lazy list.
[1] If the system doesn't support failcall, I may also have to extend 'supports-keys so that it tries 'isa-my-table. The diagram would be about twice as big if I included these predicates.
