lattice

Convergence notebook

Local updates, deterministic merges, one shared value.

lattice gives each replica a CRDT state it can update independently. When replicas meet, merge uses the CRDT's lattice rule so every node converges without locks, consensus, or a conflict-resolution callback.

GCounter merge

Merge components first. Sum only when reading.

node-a local state

{a: 2, b: 0}

node-b local state

{a: 0, b: 3}

Component-wise merged state

{a: max(2, 0), b: max(0, 3)} = {a: 2, b: 3}

Derived read valuesum(values) = 2 + 3

5

Merge compares each replica component independently. The user-facing read sums the components only after that merge.

Trace the GCounter ruleWhy merge order does not change the result

Evaluating lattice?

Take the route that answers your next question.

Understand the modelSee what CRDT convergence means and where each data type fits.Inspect package boundariesCompare the umbrella package with focused dependencies.

Choose the shape of your state.

Start from the data you need to replicate, then install the smallest package that carries that merge rule.

TotalCounterslattice_counters for values that only grow, or grow and shrink.Single valueRegisterslattice_registers for last-writer-wins or multi-value conflicts.MembershipSets + presencelattice_sets and lattice_presence for collections and live membership.Nested stateMaps + textlattice_maps, lattice_sequence, and lattice_text for keyed or ordered data.

Release status and versioning

Published lattice packages use Semantic Versioning (SemVer); current Hex releases include 1.x packages and the 3.x lattice_crdt umbrella. Pin the exact versions you validate and review release notes before upgrading, especially across major versions. lattice_fugue and lattice_text_fugue are not published to Hex yet and may change before their first release.

Prototype safely.

Verify the merge behavior your application depends on, then pin the package versions you validated. Recheck behavior and release notes before upgrading.

Quick StartBuild and merge your first counter.InstallationChoose a package, then pin the version you validate.Correctness modelReview why independent updates converge.