Let’s suppose that the only operations that we will perform on a hash table are hash-ref and hash-set!, and none of the keys is interned. Let’s even suppose that hash table values are totally disjoint from the keys. Can’t hasheq always be replaced with weak-hasheq?

The reasoning is as follows: it’s impossible to construct the key again. So that key-value entry is already lost. We might as well garbage collect it.

Is the question whether this is a legitimate use of weak-hasheq?

Not really. I do think it’s a legitimate use (but correct me if I’m wrong), but I want to know if it’s always safe to do so

The difference is too subtle to me :slightly_smiling_face: Can it be legitimate but unsafe?

What do you mean by the keys not being interned?