Erm, no, I wouldn't expect that. A hash isn't just an even-sized list. It uses a hashing algorithm (hence the name "hash") to divide the data up into a series of arbitrarily-ordered buckets. The resulting data structure is almost completely unlike a list. Why would functions designed to work on such a structure also work on lists?

The only way I can squint hard enough at it to make keys work on a list would be if keys operated by flattening the hash into a list and then iterating over every other list element. And I can't for the life of me come up with a good reason for making keys work that way.

If there really are that many use cases for iterating every other element of a list, they would be much better served by adding a new keyword for that functionality than by bloating keys with an unnecessary and anti-performant hash-to-list conversion, particularly since the new keyword could be generalized to iterate over every Nth element of the list instead of only giving "even elements" and "odd elements" options.

In reply to Re^2: Why does 'keys' need a named hash? by dsheroh
in thread Why does ‘keys’ need a named hash? by ankitpati

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