Mibo
MapCountNode<'K, 'V, 'Out> Type
A count over an adaptive map, projected through view
(the node behind AMap.count with id and AMap.isEmpty
with fun c -> c = 0). Registers nothing: the count is re-read at
the next read after a write (O(1) for a materialized source); the version
advances only when the projected output changed, so an update of an
existing key (no count change) or a count change that the projection
collapses (2 -> 3 under isEmpty) costs this node and its consumers
nothing.
No mirror is kept: the source view's Count is exact (it already
distinguishes a Set on a new key from an update of an existing one).
The view projection runs at re-sync time: keep it cheap (the built-in
uses are id and fun c -> c = 0).
Constructors
| Constructor |
Description
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Full Usage:
MapCountNode(source, view)
Parameters:
IAdaptiveMap<'K, 'V>
view : int -> 'Out
Returns: MapCountNode<'K, 'V, 'Out>
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