> 1. Is the left-fold the best/only interface to expose? I think yes, but that
> doesn't allow fine-grained control over cursors i.e. being able to open many
> cursors at once and interleave fetches from them. Or does it?
I'd like to remark first that many real databases let us avoid opening
many
The following code illustrates a _generic_ interface to low-level
database code. The left-fold iterator doQuery is completely generic
over any possible iterator -- no matter how many columns the query
returns, what are the types of these columns and what is the type of
the seed (accumulator). The
