3 ms·
> It's possible that what I mean can be turned into a statement like "all functors used in programming are representable", but I'm not sure. No, this is much s
by consilient 3y ago
> It's possible that what I mean can be turned into a statement like "all functors used in programming are representable", but I'm not sure.
No, this is much stronger and definitely false. Any variable-size data structure is not going to be representable: e.g. `Maybe`, `List`, `BinaryTree`.
Most data structures are sums of representable functors (i.e. are `Traversable`), but not all. Hash sets () are the classic counterexample: you can't walk them in a consistent order because the internal structure depends on the hashes, and you need to recompute hashes when you transform values.