Module Incremental_kernel__.Bind

A module internal to Incremental. Users should see Incremental_intf.

An ('a, 'b) Bind.t is stored inside a bind node where the left-hand side is of type 'a, and the right-hand side is of type 'b Node.t.

Each bind t has t.lhs_change : unit Node.t that is used to detect when t.lhs changes. Computing t.lhs_change restructures the graph by calling t.f and replacing t.rhs with the result.

Each bind tracks the set of nodes created on its right-hand side, as a singly-linked list t.all_nodes_created_on_rhs. This is used to invalidate all those nodes when the t.lhs changes.

The key invariant of a bind node t is:

t.lhs_change.height < node.height for all necessary nodes in t.all_nodes_created_on_rhs.

This ensures that a node created on the right-hand side is not computed unless the left-hand side is stable.

The graph manipulation done when t.lhs_change fires can't be done when t.lhs fires, because t.main could be itself created inside a bind, and this bind's lhs is not guaranteed to be stable when t.lhs fires (but it is guaranteed to be stable when t.lhs_change fires).