[FBumann]

Prompt: 1. The loader: sets: and properties:, lowered to the program's existing relation nodes, with the refusals above, the two levels of missing:, the schema regenerated, and the reference page.

Note

The following content was generated by AI.

What this changes

A file can now declare sets: and properties:. A set lowers to a bare relation with its own name. A property lowers to a relation named subject.property. An entry over a set is refused, and the message names the rewrite: the member dimensions with where:.

Why

This is PR 1 of the stack in which sets and properties replace relations. It stacks on energy-models#945 (the parameter mask).

The YAML, the lowering, and the refusals

sets:
  connection: { dims: [entity, port], missing: absent }
  cover: { dims: { generator: generator, start: snapshot, covered: snapshot }, missing: absent }
properties:
  generator: { bus: bus }                                 # short form of {into: bus}
  line: { bus0: bus, bus1: { into: bus, missing: absent } }
  connection: { bus: bus }

• A set becomes Relation(columns from dims, key = every member, missing) under its own name. So where: connection and a parameter mask that reads a set work on the paths that exist today.
• A property becomes Relation((*subject key, (name, into)), subject key, missing, subject=subject) under subject.property. No file can write a dotted name, so it collides with nothing.
• Namespace.relations holds only the names a file can write, so the error messages do not offer generator.bus. The program gets every table, through Namespace.tables.
• missing: works at two levels. On a set, it asks whether every combination of dims is a row. On a property, it asks whether every row of the subject has the property. Both take refused or absent only.
• The loader refuses:
  • an entry over a set, with the rewrite;
  • a set with fewer than two members;
  • a set that repeats a dimension without naming the members;
  • a set that names another set;
  • a member over an undeclared dimension;
  • a member named after another dimension;
  • a subject that is neither a dimension nor a set;
  • a property into a set or into an undeclared dimension;
  • a property that has the name of a key member;
  • a property named after a dimension it does not map into;
  • a property of a set that has two members over one dimension;
  • a set name that collides with another name;
  • a property name that is not a NAME.

Departures, and what this PR does not do

• Relation has a new field, subject. It is the one change to an existing node. A property of a sparse set with missing: refused means "every row of the set". The existing missing cannot say that, and an engine needs subject for the check "every property key is a row of its subject".
• override lays properties: over one subject at a time. Without that, a patch that adds a new subject crashed with an AttributeError. merge still refuses a subject or a set that appears in two fragments. Joining them is PR 3.
• No calls yet. subject[property] is PR 2. Until then, nothing in an expression reads a property.
• The typesetter prints the dotted names, as generator.bus: G → B, in all three formats. The real legend is PR 4.
• relations: stays until PR 5.

Gates, and the mutation table

• Passed: pixi run lint and pixi run test (3165 passed, 1 skipped).
• Passed: pixi run docs-build (strict). Every YAML fence on the new page loads, and the quoted refusal and the math were taken from the code's real output.
• Not run: pixi run compile-tex. Tectonic cannot download its bundle in this container, so all 54 documents failed, the existing ones included.
• Mutation table: this repo has no tools/mutate.py, so a script took the table instead. The script refuses a tree with uncommitted changes, restores each file with git checkout --, and drops __pycache__ before and after each mutation. The tree came back clean.

guard deleted	suite
entry over a set: the set rewrite	caught (3 failed)
a set has at least two members	caught
a set repeats a dimension without names	caught
a set names a set	caught
a set over an undeclared dimension	caught
a member named after another dimension	caught
a subject neither a dimension nor a set	caught (2)
a subject with two members over one dimension	caught
a property named as a key member	caught (2)
a property into a set	caught
a property into an undeclared dimension	caught
a property named after another dimension	caught
a set in the flat namespace	caught
a property name is a name	caught
missing: on a set or a property takes two words	caught (6)
missing: null on a set or a property	caught (3)
the short form of a property is written back	caught (5)
a property relation carries its subject	caught (5)
the namespace lists no property	caught
the normal form sorts each subject	caught
a patch lays over one subject at a time	caught (2)
a patch reads a short-form property as into	caught
merge names the properties of a subject	caught

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