Expressing fold in Verse Calculus

[thesz]

It appears that there is no fold (right or left) implementation in Core Verse calculus paper. From what I understand, Core Verse does not provide inter-sequence communication needed, so fold is unimplementable in Core Verse.

I guess it is possible to have folding operations implemented using effects upon a store.

So, what one should do if one needs a fold of a sequence?