B2.4.3 · dive 3 of 3 · module B2.4
One parent, no diamond.
A single :extends link makes inheritance a chain, never a lattice, so the diamond problem cannot arise. The walk is bounded by a depth cap and a cycle guard, so resolution always terminates.
The idea
echo_data · bcs/archetypes.exA bundle extends at most one parent. That single :extends link makes inheritance a chain, never a lattice, so the diamond problem — two parents disagreeing about the same property — cannot arise. Where class systems need rules to break ties between multiple bases, an archetype chain has one order and one answer.
The walk that gathers the chain is bounded and guarded. It carries a depth cap, so a chain longer than the limit is refused with :depth rather than run forever; and it carries a set of the ids it has seen, so a bundle that extends back into its own ancestry is refused with :cycle. Resolution always terminates, and it terminates with a reason when the data is malformed.
Codemojex can layer kinds without fear of ambiguity. A special tile extends a power-up that extends a base, three links in a line, and the resolved properties are deterministic; a mistake that pointed a bundle at its own descendant is caught at resolve time, not discovered as a hang. Composition is reuse with a single, ordered, terminating answer.
The doors
the sibling coursesEchoMQ — the protocol, in depth
The bus B3 narrates, taught rung by rung: the keyspace, the Lua inventory, and the 3.0 Stream Tier — XADD, XREADGROUP, XACK — with conformance on Valkey.
Redis Patterns Applied
The substrate patterns under the bus: sorted sets, atomic Lua moves, locks, and streams — the judgement layer.
/echo-persistenceEcho Persistence — the durable floor
Beneath the volatile tiers: the Graft page engine built twice, the commit-LSN loop, and the stream archive on Tigris. Where Part I says state lives somewhere, this says where it lives durably.
References
sources · relatedSources
- Helland — Life Beyond Distributed Transactions (CIDR 2007)entities as named data a system composes, not a hierarchy of code
- King — Announcing Snowflake (2010)the ARC id that names an archetype as an entity
- Erlang/OTP — the ets modulethe store a fetch reads archetype bundles from
Related
- BCS — the course homethe law, the id anatomy, the chapter map
- Echo Persistencethe durable floor beneath the bus