H : HashedTypeAdd the binding to the table, returning a new table. The old binding
for this key, if it exists, is shadowed and will be restored upon
remove tbl k.
Add the binding to the table, returning a new table. This erases
the current binding for key, if any.
update tbl key f calls f None if key doesn't belong in tbl,
f (Some v) if key -> v otherwise; If f returns None then
key is removed, else it returns Some v' and key -> v' is added.
Fresh copy of the table; the underlying structure is not shared anymore, so using both tables alternatively will be efficient.
val merge : f:(key ‑> [ `Left of 'a | `Right of 'b | `Both of 'a * 'b ] ‑> 'c option) ‑> 'a t ‑> 'b t ‑> 'c tMerge two tables together into a new table. The function's argument
correspond to values associated with the key (if present); if the
function returns None the key will not appear in the result.