Apply when writing stateful logic, or when code branches a lot or repeats a shape assumption across files. Encode the domain in a structure instead of scattered conditionals.
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What the file says
# Model the Domain
Encode the real domain in a data structure instead of scattering it across conditionals.
**Why:** Scattered booleans, repeated shape assumptions, and branching spread across files are accidental complexity. A structure that matches the domain makes invalid states unrepresentable and deletes branches. Choosing it at write time is cheap. Recovering it later reads as a refactor and gets deferred.
**Reach for structures like these:**
- A state machine instead of scattered booleans, phases, or lifecycle checks.
- A typed object/model instead of loose parameters or repeated shape assumptions.
- A map, registry, lookup table, or discriminated union instead of branching spread across files.
- A reducer or command/event model instead of ad hoc state mutations.
- A module organized around one body of domain knowledge instead of a sequence such as load, validate, transform, and save. Execution order is not ownership.
- A small module boundary that gathers repeated behavior, ownership, or invariants.
- A queue, cache, index, graph/tree, or normalized collection where the data access pattern calls for it.
…
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Source
GitHub
iap/pstack-hermes · 32 stars · license a license file GitHub does not identify · pushed 2026-11-04 · branch master
API
GET https://markdownregistry.com/api/v1/artifacts/art_epfnzu6v74cbgoc7
GET https://markdownregistry.com/api/v1/resolve?ref=iap/pstack-hermes/principle-model-the-domain
GET https://markdownregistry.com/api/v1/blob/bbadbb9a723fac3f76e782ae45665eb94058ec10993e4bae36d4dc6b0e4eac07
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