Ratchet

A delta-based CRDT join semi-lattice ratchet.

A join (or upper) semi-lattice is a partially ordered set endowed with a join operation: for any two elements, the result of the join operation is their greatest upper bound with respect to the partial order.

A Ratchet is a register whose value is the join of all assigned values: when assigning or merging, the retained value is the join of the two values. Note that join is not max: on a partially ordered set, the join of two values is not necessarily one of them.

This is a sample implementation using Strings, with default (total) ordering.

Its JSON serialization respects the following schema:

{
  "type": "Ratchet",
  "value": $value
}