Appendix B — Operator Reference

Reserved for the second edition. The exhaustive operator + precedence reference will land here once the upcoming language audit completes.

Until then, a quick overview of what the chapters have introduced.

Arithmetic

+, -, *, /, % — addition, subtraction, multiplication, division, modulo. Bind in the conventional order; parentheses disambiguate.

Comparison

==, !=, <, <=, >, >= — equality, inequality, ordering. Both sides can be expressions over bound variables and constants.

not <atom> — negation as failure. ?x in <collection> — set membership at rule-atom position. At expression position, x in xs and x not in xs desugar to <TypeOf(xs)>::contains(xs, x) (and its negation).

Collection operators

The collection-op surface is grounded in Chapter 2.8. All forms desugar at elaboration time to qualified calls into the receiver’s std::collection::* (or std::math::Range) submodule.

Token	Form	Fixity	Precedence	Desugar	Example
`.`	`xs.m(args)`	postfix	tightest (binds before any binary op)	`<TypeOf(xs)>::m(xs, args)`	`b.units.size()`
`[i]`	`xs[i]`	postfix	tightest	`<TypeOf(xs)>::at(xs, i)` (or `Map::get`)	`b.units[0]`
`[i..j]` / `[i..]` / `[..j]`	slicing	postfix	tightest	`<TypeOf(xs)>::slice(xs, Range::new(i, j))`	`b.units[0..3]`
`..`	range literal	binary infix	below `+` / `-`, above comparison	`Range::new(lo, hi)` (half-open)	`0..10`
`..=`	inclusive range literal	binary infix	same as `..`	`Range::inclusive(lo, hi)`	`0..=9`
`in`	membership	binary infix	same precedence as comparison (`==`, `<`, …)	`<TypeOf(xs)>::contains(xs, x)`	`p in b.tenants`
`not in`	non-membership	binary infix	same as `in`	`not <TypeOf(xs)>::contains(xs, x)`	`p not in b.tenants`
`[expr for x in xs where pred]`	comprehension	bracket form	bracket-bounded	`xs.filter(<pred>).map(<expr-as-closure>)`	`[u.number for u in b.units]`

Comprehensions reuse the aggregate-binding subgrammar. The where clause is optional. Binder shadowing emits OW2403.

Path

a.b.c — field-access path on a value. ?x.b.c — Datalog-binding-position field-access path on a variable.

Cardinality (inside collection types)

>= N, == N, <= N — at-least / exactly / at-most cardinality clauses. Distinct from comparison operators despite sharing tokens.

Type tests / subtype tests

v: T — match-arm type test (also a rule-atom shape). ?x specializes T — subtype predicate (rule-body only). ?x : T — rule-atom typed-binding form.

box(...) — necessity. diamond(...) — possibility. Rule-atom position.

Allen-interval operators

before, after, meets, met_by, overlaps, overlapped_by, starts, started_by, during, contains, finishes, finished_by, equals — interval-relations algebra binary infix operators.