Declare records and values
Place model declarations in Given. These fragments assume an owning app or package:
Todo { title:text trim max=200, done:bool=false }
contract Summary { count:int, total:money }
A model describes stored records with identity, version and lifecycle. A contract describes a typed structured value without introducing a stored record. Use a model reference such as customer:Customer for a relationship; copying a customer's name into a text field is a separate business snapshot.
Frequently used types include text, bool, int, decimal, money, date, datetime, duration, email, url, locale, timezone, currency, user, member and file. Use T? for a nullable value and T[] for an array. An enum(draft,submitted,approved) restricts a value to named cases.
Use decimal and money types for exact business quantities. Construct money as money(25,"EUR"); adding or comparing money requires matching currencies. Do not model currency conversion as a bare arithmetic operation: record an explicit provider result and its business decision.
Defaults, constraints and server-owned values
done:bool=false supplies a create default. A nullable field can be absent. trim, min, max and unique express supported constraints. Defaults run on creation; an omitted update leaves an existing value unchanged, and explicit null clears a nullable value.
A server initializer such as submitted_by:user server=actor binds trusted context instead of accepting a caller's claim. Do not put a server-owned field into a form's editable fields. Put rules that must hold across every mutation path into invariants and locks.
Parameter and field types remain explicit. Using a model field type on a parameter inherits its value constraints rather than its stored default or server ownership.
Query a model
These are expression fragments in a scope where Todo is visible:
Todo as task where not task.done
Todo as task where task.done order=title
count(Todo)
first(Todo as task where task.title=="Ship prototype")
Bind rows with as when you need a name in a filter or projection. first can return no result, so handle null before reading the row. count, sum, any and all provide typed collection operations. A query's row scope is distinct from the row exposed by a presentation list or a model rule.
Viewer queries apply row and field permissions before filtering, search, ordering, counts and serialization. An aggregate does not make confidential data public. A derived result must have readable dependencies. Read permissions before writing reports that summarize sensitive records.
Use typed expressions
Boolean operations are not, and and or. Comparisons include ==, !=, <, <=, > and >=; in tests membership. Use ?. for safe access and ?? for a fallback where the types permit them. Boolean operators preserve short-circuit evaluation.
Strings use JSON escapes and have no general source interpolation. Use typed formatting or localized messages. Duration literals such as 5m and 2h require the unit next to the integer. Treat a calendar date and an instant as different types; local scheduling must specify its timezone and daylight-saving behavior.
The language references own the complete type, operator and builtin definitions.